Senator Arlen Specter’s decision to caucus with the Democrats has, temporarily, pushed the “100 days” storyline into the background, and for that we should all be grateful. (For my sole media effort to correct the misperception that 100 days matter, see my brief comments with a Canadian journalist here.) In addition to the blow it inflicts on the Republican Party, at least symbolically, Specter’s defection is another reminder of how difficult it is for moderates to exist in a deeply polarized Senate. I went back and calculated Specter’s rank, using a generally accepted measure of voting-based ideology (Poole-Rosenthal scores) in each Senate session in which he served dating back to his first in 1981-83 (the 97th Congress). When it comes to voting, Specter consistently falls in the middle of the pack, with an overall average ranking across 15 congressional sessions as the 52nd most liberal Senator (standard deviation of 4.3). (Note that I include the President’s rank score in the data used to calculate Specter’s standing).
When the Senate is under Democratic control, the overall mean voting score shifts left, which tends to make Specter more conservative relative to his colleagues; his average rank under Democratic control is 57. Conversely, under Republican control, he ranks slightly more liberal, typically landing right in the middle as the 50th most liberal Senator. On the whole, then, we see that he’s a consistent middle-of-the-road Senator.
So, is his voting record likely to significantly change now that he’s a Democrat? At first glance, one might think yes. Indeed, several pundits have suggested as much based in part on political science research on previous party switchers. This research suggests that a switch in party leads to a switch in voting patterns. But caution is in order; most of this research finds significant changes only in the House. In the Senate, because of the small sample size, detecting historical trends is much more difficult.
For comparison purposes, I looked up the rankings of four other Senators who switched party affiliation in the modern era to see if it affected their overall Senate ranking.
|Senator||Years (Year Switch)||Pre-Switch Rank||Post-Switch|
|Richard Shelby||1987-2008 (1995)||61st most liberal||77th most liberal|
|Ben Campbell||1993-2004 (1995)||51||56th most liberal|
|Jim Jeffords||1989-2002 (2001)||52||52|
|Joe Lieberman||1989-2008 (2007)||37||34.5|
Keep in mind that both Shelby and Campbell switched from Democrat to Republican, while Lieberman ran as an independent after losing the Democratic primary in 2006 but did not join the Republican Party. After years as a Republican, Jeffords caucused with the Democrats in 2001 but called himself an independent. So these aren’t strictly comparable to the Specter case. (The other significant difference, as I discuss below, is that Specter’s switch is motivated by electoral reasons more than ideological ones.)
So based on this limited sample, and subject to all the caveats associated with nominate scores and using ranking, as opposed to absolute voting data (and the different time periods being compared), it appears that Shelby’s voting rank changed significantly, but the other three demonstrate less movement. When we think about the issue a bit more, it’s not surprising that this admittedly limited sample reveals no clear trend in voting patterns after a change in party affiliation among Senators, in contrast to Representatives in the House.
Remember that the House operates under rules designed to empower the majority party, so in periods of high polarization, a switch in parties should tend to lead to a switch in voting (much as political science research has found.) However, this is not necessarily the case in the Senate, where voting is less beholden to party, and much more driven by individual ideology conditioned by constituency and reelection. In other words, the Senate is not strictly comparable to a parliamentary system, where party leaders often have the means to punish those who cross party lines by, for example, removing them from party lists at election time. In the U.S. Senate, senators are largely beholden to no one except voters. Note that based on Poole-Rosenthal scores from the last (110th) Senate, Specter is the third most liberal Republican Senator, topped only by the two Maine Senators Collins and Snowe. Not surprisingly, all three Republican Senators already voted with the Democrats to pass Obama’s stimulus bill, and there wasn’t a darn thing the Republican Senate leadership could do about it.
All this is a long way of saying that I don’t expect Specter’s rather moderate voting patterns to change very much as a result of the change in party label, since he’s already signaled his willingness to cross parties and vote with the Democrats during the current session if it serves his electoral needs. Indeed that is what this switch is about – Specter’s 2010 reelection bid. By switching labels, he can run in the Democratic primary where he (so far) has at least a chance of reelection. If he stayed a Republican, he was going to get trounced in the primary (the most recent poll had him down 21% among likely Republican voters to the more conservative Pat Toomey). For Specter, becoming a Democrat was a matter of political survival – not a change in ideology. By negotiating a deal with the Democrats (including Obama’s implicit promise to back him in the Senate race), he’s hoping to avoid a challenge from the Left in the Democratic primary in two years. If so, I expect him to continue to position himself as a swing voter in a state that is trending Democratic, with his vote determined by his calculations on its likely impact on his Senate reelection chances than on party loyalty. Note also that he negotiated an agreement to retain his seniority, so the switch doesn’t cost him anything in that regard.
In short, this is a very significant switch for Specter’s electoral chances, not quite so significant for his votes in the Senate. Of course, if he gets a credible challenger on the Left in Pennsylvania, then all bets are off!
If I get a chance, I’ll talk a bit about the filibuster implications in another post. But my immediate reaction is that I don’t see this having as much impact on moving the Democrats closer toward a filibuster-proof Senate as many have surmised because Specter’s vote was already driven almost entirely by electoral, and not partisan, considerations. When it serves his purpose – as it did in the stimulus bill when he was able to leverage money to his state in exchange for his support – he will vote Democratic. But the change in party label isn’t likely to dramatically increase his propensity to do so.