A bunch of moderates on my original list lost. Jeff Perry (MA-10), Dan Debicella (CT-4), Sam Caligiuri (CT-5), Scott Bruun (OR-5) were the former state legislators who all lost. Of candidates in liberal districts, Ruth McClung (AZ-7) likely has lost.

The following list contains those who won. I added two more representatives, Bob Dold in IL-10, and Chip Cravaack in MN-8. Dold is new because he won Mark Kirk’s old district, and I was only counting pickups last time. Cravaack is new, as I didn’t expect that he’d actually defeat Democratic institution Oberstar. But both are in quite Democratic districts, and will keep that in mind when they start thinking about re-election (likely on their first day in Washington).

Former legislators (High Confidence of Moderation):

1. NH-2 (D+3): Former (and moderate) US Representative Charlie Bass won this open seat rural district that also includes Nashua and Concord.
2. NV-3 (D+2): Former state Senator and physician Joe Heck won this suburban Las Vegas district that leans Democratic, currently represented by incumbent Dina Titus. Heck was a moderate-to-liberal Republican in the state legislature, with two-thirds of his copartisans more conservative than him. Compare that to Sharron Angle, who was the most conservative state legislator in Nevada over the past decade.
3. PA-08 (D+2): Former US Representative Mike Fitzpatrick defeated incumbent Patrick Murphy. During his time in Congress, Fitzpatrick compiled a rather liberal voting record, on par with Chris Shays of Connecticut, and more liberal than Joseph Cao’s.
4. IL-14 (R+1): State Senator Randy Hultgren is won this Northern Illinois district that is currently represented by Democrat Bill Foster. In the Illinois state legislature, Hultgren compiled a conservative-for-Illinois record, that in national terms is moderate-to-liberal, or about where Scott Brown is.

No legislative experience (Medium Confidence of Moderation):

1. IL-10 (D+6): Bob Dold beat 3-time candidate Dan Seals in this liberal district containing Chicago’s Northern Shore suburbs. It was previously represented by moderate Mark Kirk, who just won Obama’s old Senate seat.
2. CA-20 (D+5): Farmer Andy Vidak has very likely beat liberal incumbent Jim Costa in this highly Democratic district covering Fresno and Kings County, following a new SurveyUSA poll that puts him up 10.
3. PA-11 (D+4): Hazleton Mayor Lou Barletta defeated Paul Kanjorski in this district that includes Scranton and Wilkes-Barre.
4. IL-17 (D+3): Pizza businessman Bobby Schilling is won this district in Western Illinois that stretches all the way to Aurora and Elgin. The current incumbent is two-term Phil Hare.
5. PA-07 (D+3): Prosecutor Pat Meehan beat former state legislator and prosecutor Bryan Lentz in this suburban Delaware County district, formerly held by Joe Sestak who defeated Arlen Specter in the Democratic primary this year.
6. WI-07 (D+3): Prosecutor (and former reality star) Sean Duffy won in this rural western Wisconsin district, after four-decade incumbent David Obey retired.
7. MN-8 (D+3): Pilot Chip Cravaack defeated incumbent Jim Oberstar, who had represented the district since 1975.

Overall, we have 11 new moderates elected from the more than 60 newly elected Republican representatives. That’s not a trivial amount, but neither is it nonexistent. Not all the Republicans of the class of 2010 are hard core conservatives.

One thing that struck me on this list is the presence of Illinois and Pennsylvania, each with three new probable moderates. Incidentally, I met the Illinois three on a taping on WTTW’s Chicago Tonight program, where I talked about the election with longtime host Phil Ponce. You can see them here.

How will that happen? On this election day, I’ll detail one path that has received relatively little attention.

While everyone focuses on the Republicans’ pickup opportunities—of which there are many in the Senate and the House—fewer observers have taken a cumulative look at the consequences of open seats won by the incumbent party. That is, when a Republican replaces a retiring (or defeated) Republican, and similarly for Democrats. Since not all partisans are alike ideologically, it behooves us to examine more closely who is replacing whom.

I will address Senators today, and only Republicans. I will focus in this post on the latter for a very simple reason. Because of the coming Republican wave, only three Democratic open seats exist which other Democrats have a (virtual) lock on. These are Connecticut, Delaware, and West Virginia. The former are both liberal states, but I have no prior legislative voting behavior to predict the likely ideologies of Richard Blumenthal and Chris Coons, respectively, with respect to the incumbents Chris Dodd and Joseph Biden/Ted Kaufman. Nor can I tell if WV Governor Joe Manchin will be more or less liberal than Carte Goodwin, Robert Byrd’s replacement by Manchin himself.

So are the new Republican Senators going to be more conservative in the 112th Congress? Based on evidence culled from my research, and a little speculation, I will say yes with a large degree of confidence.

To proceed, I will divide Republican open seats going Republican (ROSGR) into five categories, based on the state of evidence that the seat is becoming more conservative, or not.

In the first category are those ROSGRs that I have strong evidence are becoming more conservative. This is because of the well-known finding in political science by Keith Poole and Howard Rosenthal that politicians “die in their ideological boots” (see here for an ungated version of Keith’s paper). That is, politicians rarely change their stripes. Thus, we can look at their prior voting records in other legislative chambers—federal and state—to predict their Senatorial ideology.

1. Florida. Incumbent Mel Martinez retired and was replaced by George LeMieux (via a pick by Governor Crist). Both were moderately conservative; about three quarters of congressional Republicans were to their right. Marco Rubio, former speaker of the Florida House of Representatives and victor against Crist in the Republican primary, is a few clicks to their right (but less than I’d expected).
2. Missouri. Retiring Kit Bond is a moderate; he’s about as conservative as LeMieux or former Senators Spencer Abraham or Pete Domenici. Roy Blunt is the current Representative and minority whip from the 7th Congressional District in Missouri. He’s also the likely victor on Tuesday. He’s compiled a voting record that’s 20 percentiles more conservative than Bond, about in the range of Mike Enzi of Wyoming.
3. Ohio. Retiring George Voinovich was one of the most liberal Republicans in the Senate. Representative Rob Portman (OH-2) , his nearly-guaranteed successor, is 20 percentiles more conservative. His ideology is about the same as that of former Senator and majority leader Bill Frist.

In the second category, we have ROSGRs where I have informed speculation and a strong degree of confidence (but not nearly so much as the first category where I have evidence) that will be more conservative than the previous incumbents. Both are the open seats resulting from the defeat of incumbents in primaries, on grounds that the latter were too liberal.

1. Utah. Senator Bob Bennett is in the moderate half of congressional Republicans; that’s still pretty conservative by national standards. Still, Utah is one of the most—if not the most—conservative states in the union. It can electorally support a much more conservative Senator. While I have no voting record for Mike Lee, every bit of evidence from the Republican primary tells me that he’s likely to be far more conservative.
2. Alaska. Assuming Joe Miller wins, that means he’d replace Lisa Murkowski, a decidedly moderate Republican. The primary and general campaigns have clearly staked ideological territory where Miller is to the right of Alaska. As in Utah, Alaska is one of the most conservative states in the US; it can easily support a more conservative Senator.

In the third category, we have a ROSGR where I’m making an informed guess with less confidence than the previous category. There’s only one of these:

1. Kentucky. Jim Bunning is a pretty conservative Republican; only about a fifth of congressional Republicans are more to the right. That causes me to move this race out of the last category. On the other hand, Republican nominee Rand Paul is running a distinctly ideologically conservative and libertarian campaign. This leads me to believe he’d be more conservative than Bunning, but I’m not as sure.

In the fourth category, we have a ROSGR where I have evidence that there won’t be much change in ideology after the incumbent leaves. There’s only one of these.

1. Kansas. Despite his reputation, Sam Brownback is about in the middle of his party for conservatism, and is retiring to run for governor. Representative Jerry Moran (KS-1) is a lock to win Brownback’s seat, and he’s just about as conservative.

In the last category, we have the Republican counterpart to Delaware and Connecticut: a race where I have no evidence nor good speculation about how the winner will compare to the retiring incumbent.

1. New Hampshire. Judd Gregg is a moderate Republican, but that’s probably about the carrying capacity of the state for conservatism. Kelly Ayotte is the former state attorney general, and not much can be gleaned from the campaign (apart from her defeat of more Tea Party-favored Ovide Lamontagne).

So, to sum up, of the eight open seats being vacated by Republicans and likely taken again by Republicans, 5 will become more conservative with a high degree of confidence, 1 will become more conservative with a medium degree of confidence, 1 will stay the same, and 1 is unclear.

Moreover, I didn’t include Pennsylvania’s Arlen Specter, who quite clearly would have been an example of a ROSGR had he remained a Republican. He was the most liberal Republican in the Senate at the beginning of the 111th Congress–more liberal than either Susan Collins or Olympia Snowe. Had he stayed a Republican, he would most likely have been defeated in a primary by Representative Pat Toomey (PA-15), which would have set up the same general election we are seeing today. Likely victor Toomey is very conservative; only 20 percent of Republicans are more to the right. In fact, I see him as more conservative even than Rick Santorum. So, depending on how you look at this case, the case for ROSGRs going more conservative is even stronger.

All of this is one reason why the 112th Republicans will be the most conservative, and the 112th Congress will be the most polarized yet. This is the “dog-bites-man” story; while the “man-bites-dog” story of the coming liberal House Republicans is merely an entertaining sideshow.

There’s only one thing I wonder about. Even if everything Boris writes is correct–and I have no reason to doubt him–he’s still only coming up with 10 moderate Republicans, out of a total of 200 or so. That’s not a lot.

Well, I found two more (Debicella in CT-4 and Bruun in OR-5), so it’s now 12. Of course, not all of them will get elected, so only a fraction of those will get a chance to be the fightin’ moderates of the Republican Class of 2010.

Congress has been getting more ideologically polarized since the 1950s, with a dramatic rise since the mid-1970s. This means that Democrats are becoming ever more liberal, and Republicans are becoming ever more conservative. In the 110th Congress, both the House and the Senate are more polarized than they have ever been (since the Civil War and Reconstruction). The 111th was more polarized still. Here’s Nolan McCarty’s plot of Congressional polarization:

I predict the 112th will be the most polarized yet. That’s not saying much; the trend has been very strong. Or in other words, the story of increasingly conservative Republicans is “dog bites man.” However, in a wave election, quite a few liberal districts and/or liberal candidates from the winning side will get through. In 2010, that’ll be liberal Republicans; in 2006 and 2008, it was conservative Democrats. That’s “man bites dog,” and therefore newsworthy in its own right (or so I think as an amateur journalist).

Nolan McCarty, Keith Poole, and Howard Rosenthal, in a 2009 AJPS paper identify the advance of polarization by two paths: 1) districts electing representatives more like them (eg, liberal districts electing liberals and conservative districts election conservatives), and 2) for a given district, Democrats becoming more liberal, and Republicans more conservative. The former effect is called sorting and the latter effect is called divergence. Here’s a freely accessible but older version of the paper; the final version is gated here.

Of course, the irony is that these moderate and liberal Republicans will be uniquely vulnerable in the post-wave elections of 2012 and beyond. Djou and Cao, for example, got in under extraordinary circumstance; so will some of the Fightin’ Liberal 12 I identified. That’s the sorting effect which has been cutting down on the number of liberal Republicans and conservative Democrats in the past few decades.

But once they’re defeated, they’ll be replaced by considerably more liberal Democrats. Until then, they are considerably more conservative than the Democrats they have or will have defeated. This is the divergence effect.

Thus, Djou is undoubtedly a liberal Republican in HI-1. But Colleen Hanabusa is much, much more liberal, as shown in her voting record as a Hawaii state senator. If she attains office, she’d be as liberal as Senator Patty Murray (WA) or Senator Patrick Leahy (VT). Thus, conservatives have to face the fact that the alternative to electing a liberal Republican is often electing an even more liberal Democrat.

Republicans, in this wave election that recalls 1994, look set to win not just swing districts, but also those districts that have been traditionally Democratic, or those with strong or longtime Democratic incumbents. Naturally, just as in 2008, this has led to overclaiming by jubilant conservatives and distraught liberals–though the adjectives were then reversed–that this portends a realignment in American politics.

What do Republican inroads in traditionally Democratic areas portend for how these potential new Representatives will vote come January 2011? For a little guidance, think back to two Republicans who won special elections in deeply blue constituencies in the 111th Congress: Scott Brown in Massachusetts, and Charles Djou in Hawaii’s 1st District.

I’ve already written a bit about Scott Brown. My prediction after his election but before his arrival in Washington was that Brown, based on his voting record in the Massachusetts state legislature, would prove to be one of the most liberal Republicans in the US Senate, for which I was vilified a bit online. Now that we have nearly a year’s worth of votes behind us, I feel pretty good about that prediction. My estimate of Brown’s ideology—using our NPAT common space data–is that he is the third most liberal Republican in the Senate, just behind Olympia Snowe and Susan Collins of Maine.

Charles Djou won a unique special election in the normally very Democratic HI-1 district, when two Democrats split the majority of votes in the district due to the lack of a primary election by law. One measure, among many, of the partisan leanings of a district is its Cook Partisan Voting Index or PVI score. HI-1, which is Barack Obama’s home district and encompasses Honolulu, is D+11. I hadn’t yet written about Djou–to my regret—though he had previously served in the Hawaii State Assembly (District 47). While there, he compiled a conservative-for-Hawaii voting record; I estimate him in the top 10 percent of legislators for conservatism in the state. He was even right of center of his own party.

Of course, the punch line is just like that for Dede Scozzafava in New York. A conservative Republican in Hawaii just ain’t that conservative when you look across the country. It’s just that Hawaii Republicans are quite liberal. Based purely on Djou’s voting record in the Assembly, I would have predicted him to be more liberal than Lincoln Chaffee (RI) or Jim Jeffords (VT), the first of whom endorsed a Democrat for president, and the second of whom gave majority control of the Senate to Democrats by leaving the Republican party. In fact, he turned out to be slightly more conservative than I had expected, but not by much. He’s about as conservative as Scott Brown is–that is, not very–by the standards of congressional Republicans.

In fact, the only Republican representative evincing a more liberal voting record than Djou is Anh “Joseph” Cao, of Louisiana’s 2nd District. Cao won his New Orleans district after the indictment of his predecessor. Yet even his sole Republican vote in favor of the Democratic health care reform legislation doesn’t appear to be enough to save him, as polling and other data indicate a very high likelihood of a Cao loss.

In short, Republican moderates in Congress are often associated with two factors: 1) a liberal voting record earlier in their career, and 2) a liberal district. Of course, both are related, in the sense that ambitious moderates choose liberal districts to run in, and liberal districts weed out conservative candidates. Still, district opinion and legislator ideology are not always mirror images, for reasons I will describe in a later post. Despite this, Republican liberals and moderates often find themselves in difficult electoral contests, as Democratic conservatives and moderates are discovering anew in 2010.

Given how competitive Republicans are in 2010, even in otherwise unfriendly territory, we should then expect a crop of moderates to emerge in the 112th Congress that will vote on the left side of the party.

So which Republican candidates are likely to be the fightin’ moderates of the freshman Republican class of 2010? I combed the list of candidates in the House for Republicans who have a nontrivial shot of defeating a Democratic incumbent, yet who will do so in the context of a past liberal voting record, and/or a district that leans left.

Former legislators:

1. MA-10 (D+5): Former state legislator Jeff Perry has a good chance of beating Bill Keating for this open seat centered around Cape Cod (which was Bill Delahunt’s old seat). Perry is remarkably similar to Brown, in that he is conservative for a Massachusetts Republican, but very liberal compared to legislators nationally and those in the US Congress. He’s about as liberal as Arlen Specter was before his switch to the Democrats.
2. CT-4 (D+5): State Senator and Deputy Minority Leader Dan Debicella has a chance to defeat incumbent Jim Himes, who himself defeated conservative-nemesis Chris Shays in this southwestern Democratic district containing Stamford and Bridgeport. Debicella is one of the most conservative Democrats in the state legislature. That’s not saying too much given how liberal CT Republicans are; he’s about as conservative as Lisa Murkowski.
3. NH-2 (D+3): Former (and moderate) US Representative Charlie Bass is a toss-up to win this open seat rural district that also includes Nashua and Concord.
4. CT-5 (D+2): State Senator Sam Caligiuri has a small chance to defeat incumbent Chris Murphy in this Northwestern Connecticut district, including the town of Waterbury. If he does, Caligiuri is going to have the distinction of being the most liberal Republican in Congress since at least 1993. And that’s coming from a conservative for CT Republican state senator. Wow.
5. NV-3 (D+2): Former state Senator and physician Joe Heck is favored to win this suburban Las Vegas district that leans Democratic, currently represented by incumbent Dina Titus. Heck was a moderate-to-liberal Republican in the state legislature, with two-thirds of his copartisans more conservative than him. Compare that to Sharron Angle, who was the most conservative state legislator in Nevada over the past decade.
6. PA-08 (D+2): Former US Representative Mike Fitzpatrick is favored to defeat incumbent Patrick Murphy. During his time in Congress, Fitzpatrick compiled a rather liberal voting record, on par with Chris Shays of Connecticut, and more liberal than Joseph Cao’s.
7. OR-5 (D+1): State Representative Scott Bruun is favored to win this district that runs from the central coast to Salem and north to the Portland suburbs. It has been held by Democrats since the 1996 elections. Bruun is a liberal Republican in the state legislature; 70 percent of his copartisans are more conservative. He’s about as conservative as Scott Brown or Mike Castle.
8. IL-14 (R+1): State Senator Randy Hultgren is favored to win this Northern Illinois district that is currently represented by Democrat Bill Foster. In the Illinois state legislature, Hultgren compiled a conservative-for-Illinois record, that in national terms is moderate-to-liberal, or about where Scott Brown is.

No legislative experience:

1. AZ-7 (D+6): Rocket scientist and first time candidate Ruth McClung has a small but decent chance of beating liberal icon and incumbent Raul Grijalva in this majority Latino district that contains Yuma county.
2. CA-20 (D+5): Farmer Andy Vidak is suddenly in a toss-up with liberal incumbent Jim Costa in this highly Democratic district covering Fresno and Kings County, following a new SurveyUSA poll that puts him up 10.
3. PA-11 (D+4): Hazleton Mayor Lou Barletta faces incumbent Paul Kanjorski and is favored to win this district that includes Scranton and Wilkes-Barre.
4. IL-17 (D+3): Pizza businessman Bobby Schilling is favored to win this district in Western Illinois that stretches all the way to Aurora and Elgin. The current incumbent is two-term Phil Hare.
5. PA-07 (D+3): Prosecutor Pat Meehan is heavily favored against former state legislator and prosecutor Bryan Lentz in this suburban Delaware County district, formerly held by Joe Sestak who defeated Arlen Specter in the Democratic primary this year.
6. WI-07 (D+3): Prosecutor (and former reality star) Sean Duffy is heavily favored to defeat Julie Lassa in this rural western Wisconsin district, after four-decade incumbent David Obey retired.

Look for these candidates–once they win—to magically accumulate moderate and liberal voting records once they realize the next election is only two years away, in rather dangerous territory. Or alternatively, that their campaign rhetoric is one thing, and their personal (moderate-to-liberal) policy preferences are quite another.

The second reason this is big news is the sea change in ideology this election implies. Oliverio is conservative. No, really, really super duper conservative. According to Wikipedia, he’s pro-life, and supports a state constitutional ban on gay marriage. He serves as one of the WV chairs of the libertarian/conservative American Legislative Exchange Council, which aims to “to advance the Jeffersonian principles of free markets, limited government, federalism, and individual liberty”, and which features a button on how to “crack ACORN in your state” on its home page. And George W. Bush explicitly name-checked Oliverio for his support of the Sam Alito nomination to the US Supreme court.

Exactly how conservative is he? Our common space score for him is 0.25, which puts him into the 96th percentile of his party for conservatism in his state for the last decade or so. He’s about as conservative as the average WV state Republican, and more conservative than many of them.

If he wins the general election in November, he’d be replacing Mollohan, who scores a pretty liberal –0.5 (remember that these scores put Congress and state legislatures onto a common scale for comparisons). That’s average for WV Democrats over the past 15 years or so.

For comparison, if Oliverio were to remain ideologically consistent (something I consider very likely for all “graduating” state legislators), he’d be more conservative than the sole Republican in the state delegation to Congress, Shelley Capito. He’d be more conservative than a bunch of other Republicans, too. He’d be far more conservative than the most conservative Democrat in Congress, Idaho’s Walt Minnick, who voted against health care reform, the stimulus, and the Waxman-Markey environment bill.

That’d be amazing. Remember, in our polarized times, no Republican in Congress is to the left of any Democrat (and, vice versa, no Democrat is to the right of any Republican). If elected to Congress, Oliverio could be the first conservative Democrat in a long time to make at least some Republicans look liberal.

Some of the conservative reaction has been of resigned sighs, but others were more outraged. But re-election as a Republican in Massachusetts isn’t going to be easy in 2012, even with a massive war chest. Expect more of these votes.

Political science is mostly about explanation, not prediction. But I couldn’t help myself on this one. Of course, it’s just one vote. We await more votes to see where he really lines up relative to his new colleagues. And his campaign rhetoric (and ideology) will make it very difficult for him to vote for the Senate (or Obama’s) version of health care reform.

Update 2/25: That was fast. Hours after my post, Stanford’s Simon Jackman posts his first estimate of Brown’s ideal point. And, lo and behold, he’s the leftmost Republican, as per my prediction. Of course, with so few votes, it’s a necessarily noisy estimate. Here it is:

The dots are the best estimate, and the lines are the uncertainty around that estimate. So Brown could be as conservative as Lisa Murkowski (R-AK), but he could also be as liberal as Robert Byrd (D-WV). Again, things will change as more votes happen, but you heard it here first.

Despite support from the Republican Governor and Democratic Senate Leader Darrell Steinberg, Maldonado faces a very difficult confirmation. Democrats accuse him of being too conservative. At the same time, the influential California Republican Assembly recently called for his defeat.

Can they both be right? Can Maldonado be simultaneously liberal and conservative? Yes. But only in California!

In a series of recent posts, I showed a plot putting state legislatures and their parties on a common scale. I was able to compare how liberal or conservative these legislatures were over the past decade and a half or so, and also how polarized they were. I measured polarization as the distance between the centers (medians) of the two parties, and I compared these legislatures to the US Congress (which many people these days claim is so polarized it can barely function).

California stands out in that plot for its polarized nature. Democrats in California are really, really liberal. And Republicans are really, really conservative. The state legislature as a whole is very liberal, because of the dominance of the Democrats in this time period. This is in contrast to other liberal state legislatures that aren’t particularly polarized: for example, New York, New Jersey, Massachussetts, Hawaii, Connecticut. There, Democrats are liberal, and Republicans are, too (like Scott Brown).

And, as I mentioned in piece published in the Sacramento Bee, California’s polarization makes Congress’ polarization look like “tiddlywinks.”

California’s polarized legislature has been well known and studied (here’s a great book on the topic by Seth Masket at the University of Denver, or UCSD’s Thad Kousser), but this is the first time we can make these sorts of comparisons. The state really does stand out.

Back to the matter at hand. Maldonado is a very curious sort of Republican in California. We’ve known from his voting record that he’s a maverick in the party. For example, a year ago, Maldonado switched his vote to support a budget plan that had been agreed to by Democratic leaders and the Governor, but opposed by nearly every Republican.

But exactly how liberal or conservative is he? My research, along with Princeton’s Nolan McCarty, allows us to estimate very precisely the ideology of individual state legislators across the country. To do so, I use the entirety of 50 state legislative voting records, and I make them comparable by calibrating them through Project Votesmart’s candidate surveys.

And our ideological scoring system places him at 0.47. Looking at the plot above, you can visually see that he’s at the leftmost end of the Republican party distribution in California. Actually, he’s in the most liberal 3rd percentile in the party. That is, 97% of all Republicans who have served between 1993 and 2006 in either the Assembly or the Senate are more conservative than him.

But his voting record is only that liberal in a state like California’s. He’s by far more conservative than even the most right-wing Democrat in the state. And if you sweep your eyes up the plot from the leftmost “whisker” of the Republican party in the state, you’ll see that California Republican liberals are largely mainstream (if only slightly center-left) Republicans elsewhere. For a comparison, Maldonado is far more conservative than Scott Brown, who scores at –0.17.

It is perhaps not surprising that Governor Schwarzenegger, who’s fairly moderate himself, would nominate a Republican like Maldonado. I’ll leave it to others to figure out the strategic games. But I’ll only note that California Democrats can’t hope to find a more suitable Republican – something the relatively liberal Los Angeles Times editorial page has figured out.

To sum up, Senator Maldonado is simultaneously liberal (to California Republicans), conservative (to California Democrats), and moderate (compared with Republicans in the rest of the country). Again … only in California.

Update 2/12/10 — Sorry, comments were turned off for some reason … They’re back on now.

My comparative research design allowed me to place him to the left of Dede Scozzafava, even though the two had never served together. It also allows me to put Brown on the same ideological scale with members of Congress, so I can make an informed prediction about how he’ll vote when he joins the Senate.

In particular, based upon his voting record in the Massachusetts State Senate as well the Votesmart surveys of MA state legislators (include his own from 2002), I estimate that Brown is to the left of the previously leftmost Republican in the Senate, Olympia Snowe of Maine (see her issue positions here) and to the right of the rightmost Democrat in the Senate, Ben Nelson of Nebraska (issue positions here). Just as important, Brown stands to become the pivotal member of the Senate—that is, the 60th by rank most liberal (equivalently, the 41st most conservative)–a distinction previously held by Nelson.

These figures come thanks to the hard work of UCLA political scientist Jeff Lewis who keeps an archive of almost up-to-the-minute votes in Congress, and Stanford political scientist Simon Jackman who calculates current ideological scores for all members of Congress in the current 111th Congress, past and present.

By dropping Senators no longer in office in this Congress, I created a dual Google Docs spreadsheet ranking of current US Senators before Brown’s election, and afterwards. It can be found here. The crucial columns to focus on are the first one, containing the ranking, and the third one, containing Jackman’s best estimate of their ideology (the final three columns express the uncertainty surrounding the estimates – ignore this for now). For a graphic version of this data, click here.

Before yesterday’s election, the 60th senator was Ben Nelson. This ranking made Nelson uniquely powerful–in political science we call this power pivotality. It’s a very useful insight into how Congress works. Nelson was pivotal because, on any divisive legislative votes, his vote could either provide the crucial 60th vote to cut off a filibuster, or the crucial 41st vote to sustain one. And of course, without the Senate, there’s no new law. Thus, it’s not a surprise that Nelson was such a central figure in the health care debate, and why the President expended no little effort in trying to convince Nelson to come on board, which he finally did in the wake of a sweetheart deal for his state.

After Brown’s election, however, the picture changes. Paul Kirk–the appointed temporary replacement for Edward Kennedy–estimated to be the third most liberal Senator, leaves. Brown, who’s to the left of Snowe but to the right of Nelson, enters. He therefore becomes that pivotal 41st vote to sustain a filibuster and deadlock legislation (or the 60th vote to end a filibuster and pass it).

How far to the left of Snowe and how far to the right of Nelson is Brown? It’s difficult to tell exactly. In the spreadsheet, I put his score (in Jackman’s scale) at 0.299, or a smidgen to the left of Snowe (0.300). But he could just as well be just a touch to the right of Nelson (0.138), too. And his drifts left and right will be watched very carefully by President Obama and Congressional and party leaders, given his likely newfound status as the filibuster pivot. That’s a lot of power.

Thus, I disagree with Josh Tucker that the election isn’t that consequential. First, the pivotal Senator will now be a Republican, not a Democrat. The parties put a lot of pressure on moderate members of Congress to vote one way or the other; it’s often unsuccessful, but its a pretty powerful source of influence. Second, that pivotal Senator will be Brown, not Snowe (if my prediction proves accurate). Finally, this pivotality will exist on every issue, not just health care reform, which probably just expired in its current form. Not too shabby as a consequential election, right?

Could I be wrong? Yes. It’s possible Brown turns out to be more conservative than we would have expected given his rather liberal state legislative record. At last night’s victory speech, he laid out a number of conservative policy positions.

The observation that politicians are ideologically consistent as they move throughout their careers (“they die with their ideological boots on” in Keith Poole’s memorable phrase) is true on average, not in every case. What could make him more conservative? The party could pull him in that direction. Or maybe presidential considerations (Obama has made the hearts of all State Senators full with ambition) will pull him to the right.

But let’s be realistic. Scott Brown is a politician, not a kamikaze pilot. As David Mayhew argued in 1974, the first and proximate goal of politicians in the United States is to get re-elected. Brown will have a far harder time in 2012 against some credible, seasoned Democrat who won’t get surprised again (or run so badly). Turnout will be higher in that presidential year, meaning the Democratic base will be far more evident at the polls. And the Democrat will get to ride Obama’s coattails, influencing independents in the Democratic direction. And Brown doesn’t have that many years to build up the incumbency advantages that other freshman Senators get. He won’t have brought home as much bacon, and he won’t have risen too far in Congress.

All in all, 2012 will be a very tough election for Brown. So what will the soon-to-be-worried Senator do to enhance his electoral chances? He’ll take the public opinion pulse of his state very, very carefully. And his state is amongst the most liberal in the country. Unless he aims to run for President in 2012 (pro-choice Republicans do well in Republican primaries, right?), his liberal constituency and a desire for re-election will inevitably pull him to the left. Sure, he is far more conservative than Kennedy, Kirk, or Coakley, but that’s immaterial. Brown’s a liberal Republican, and now he’s pivotal.

The election is particularly noteworthy for a number of reasons. First, recent polls show Brown matching or even exceeding Coakley’s electoral support, in one of the most liberal states in the entire country (and one that hasn’t elected a Republican in four decades). See Pollster.com’s aggregation of polls here, and Intrade’s political market for the election here. Second, the consequences of a Brown victory could be the derailment of the Democratic health care reform proposal, if all Senate Republicans maintain party unity.

To my mind, the election is fascinating for another reason. Brown is attracting very positive national and state Republican and conservative attention. On the other hand, State Assemblywoman Dede Scozzafava attracted very negative attention from conservatives in her special election campaign for the 23rd Congressional District of New York.

Brown is actually a liberal Republican who is to be found to the left of Dede Scozzafava! So why, then, the enthusiasm gap in support for the two? This post documents this assertion, and then answers this puzzle.

Citing my ongoing research on ideology in state legislatures in an earlier blog post, I made some waves by arguing that Scozzafava was actually a conservative Republican in a particular context. That context was the New York State legislature, where Republicans are exceedingly liberal relative to the rest of the country. In fact, she was actually located slightly to the right of the average Republican in the legislature. Despite this, there was a firestorm of opposition to her, leading to an insurgent challenge by Doug Hoffman under the Conservative Party label and her subsequent withdrawal from the campaign.

What about Scott Brown? How liberal or conservative is he? We have evidence from multiple sources. The Boston Globe, in its editorial endorsing Coakley, called Brown “in the mode of the national GOP.” Liberal bloggers have tried to tie him to the Tea Party movement, making him out to be very conservative. Chuck Shumer called him “far-right.”

In 2002, he filled out a Votesmart survey on his policy positions in the context of running for the State Senate. Looking through the answers doesn’t reveal too much beyond that he is a pro-choice, anti-tax, pro-gun Republican. His interest group ratings are all over the map. Business and gun rights groups typically rate him very highly, labor and and environmental groups have rated him both middling and high over time. The teacher’s union rated him low in 2001, and high in 2005.

All in all, a very confusing assessment, and quite imprecise. So how do we compare Brown to other state legislators, or more generally to other politicians across the country? My research, along with Princeton’s Nolan McCarty, allows us to make precisely these comparisons. Essentially, I use the entirety of state legislative voting records across the country, and I make them comparable by calibrating them through Project Votesmart’s candidate surveys.

By doing so, I can estimate Brown’s ideological score very precisely. It turns out that his score is –0.17, compared with her score of 0.02. Liberals have lower scores; conservatives higher ones.

Brown’s score puts him at the 34th percentile of his party in Massachusetts over the 1995-2006 time period. In other words, two thirds of other Massachusetts Republican state legislators were more conservative than he was. This is evidence for my claim that he’s a liberal even in his own party. What’s remarkable about this is the fact that Massachusetts Republicans are the most, or nearly the most, liberal Republicans in the entire country!

Of course, while the Republicans here are liberal, Democrats are incredibly liberal. In comparison to them, Brown is a conservative. He was also the most conservative of the tiny handful of Republican State Senators.

Perhaps the most important context in which Brown can be considered a conservative is the electoral one. We’re talking about Massachusetts here, one of the most liberal states in the country, delivering 62% of the vote for Barack Obama, in comparison to 36% of the vote for John McCain. And as liberal as Brown may be, he’d be far more conservative than Edward Kennedy (-.92), or Martha Coakley (no score as she has never been a legislator, nor has she filled out the Votesmart survey – but ACORN has given her its top rating). And the third party candidate here, Libertarian Joseph L. Kennedy (no relation to the famous ones), is not a viable candidate nor is he palatable to mainstream conservatives relative to Brown.

In other words, what began as a puzzle turns out not to be much of oneat all. It makes perfect sense that Scott Brown, a liberal Massachusetts Republican, has attracted Republican and conservative support. He’s perfectly suited for his liberal state electorate. Dede Scozzafava, in fact considerably more conservative than Scott Brown was not nearly so well matched to her intended constituency, the relatively conservative 23rd District that had returned moderate conservative John McHugh since the 1992 election.

What this shows, however, is that the conservative base in the United States, far from dragging their party moblike into an unelectable extreme, has made the decentralized decision to support the realistically best candidate they can relative to the context in which he’s being elected. The 23rd special district election can also be seen in this light; throwing Scozzafava overboard made far more sense in the context of that electorate.

John Tanner (D-TN) is retiring from the 8th congressional district in 2010. He’s best known as one of the founders of the moderate/conservative Blue Dog Democrats in the House. Running to succeed him is Roy Herron, a Tennessee State Senator who was a former minister.

Josh Kraushaar, a writer at Politico.com, writes that Herron is to the left of Tanner, which would be a disadvantage in the fairly conservative district. He points to Herron’s authorship of a book called “How can a Christian Be in Politics?” which he interprets as a progressive call-to-arms for the faithful.

But what about their voting records? Tanner is definitely a conservative Democrat; most recently, he voted against the House leadership’s health care bill that passed by a mere five votes. Herron, on the other hand voted, recently voted in favor of legislation that would allow concealed weapons in restaurants serving alcohol (over the veto of the governor).

In my research on state legislative ideology (papers here), I am able to put state legislators and members of Congress on the same scale. In this case, Kraushaar and the Politico are wrong. Tanner scores at –0.38, considerably more conservative than the Democratic average of –0.81 from the 103rd-111th Congresses. But Herron scores at -0.26, or slightly more conservative than the incumbent Tanner.

While Herron would be a conservative Democratic in Congress if elected, he’s a moderate Democratic in Tennessee, where Democrats are quite conservative (eg, more so than their counterparts in Kansas or Missouri).

Update: More evidence that I’m right from The Hill. A review by Publisher’s Weekly made references to “liberal causes” that Herron supports. That review was republished on Herron’s website, minus that phrase. Talk about knowing your electorate!