Political Science Research on Party Switching

by John Sides on April 28, 2009 · 3 comments

in Legislative Politics,Political science

nokken.png

I seek to determine whether or not political parties have significant independent effects upon the roll-call behavior of their members. Taking advantage of a natural experiment, I analyze the roll-call behavior of those members of the House and Senate from 1947 to 1997 who changed party affiliation while in office. Using data from the 80th to 105th Congresses, I find that Democrats who become Republicans, for instance, start to vote like Republicans at the time they “cross aisles.” This finding is consistent with the claims made in a growing literature that emphasizes the partisan aspects of congressional organization, and it supports the contention that party plays a direct role in determining members’ roll-call behavior.

The paper is by Timothy Nokken (gated). I’ve posted his graphs of what happened to Ben Nighthorse Campbell and Richard Shelby after their switch to the Republican Party. Pretty dramatic changes in party support.

Here is the abstract of a second paper:

In this paper, we analyze the roll call voting behavior of those House and Senate members who changed their party affiliation during the course of their political career. We analyze members who switched during the stable periods of the three major twoparty systems in American history: the Federalist-Jeffersonian Republican system (3rd to 12th Congresses), the Democratic-Whig System (20th to 30th Congresses), and the Democratic-Republican System (46th to 106th Congresses). Our primary finding is that the biggest changes in the roll call voting behavior of party defectors is observed during periods of high ideological polarization, and that party defections of the past 30 years are distinct from switches in other eras due both to high polarization and the disappearance of a second dimension of ideological conflict.

That’s by Timothy Nokken and Keith Poole. The paper is here. Their findings suggest that Specter’s voting behavior will shift, as the parties are quite polarized in both chambers.

A third paper, by Gary King and Gerald Benjamin, speaks to why members of Congress switch parties. They argue that “ideological dissonance” and electoral circumstances help explain party switching:

It is a basic premise of this study that politicians who switch parties are likely to do so when they are ideologically out of line with their current political party and more in agreement with the other party. Nor do we quarrel with the notion that sometimes the switch may also be related to electoral incentives.

Of course, lots of people fit this bill but don’t switch. King and Benjamin argue that this is because switching typically entails a combination of pressures:

Estimates from our statistical models indicate that switching is often explainable by systematic variables representing pressure on the legislators from the external, electoral, and congressional environments. Large changes in these three categories of variables each led to only fractional increases in the propensity of members to switch. It is only when there were large amounts of political stress coming simultaneously from several of these categories—such as is the case during critical realignments—that there is enough reason to cause members to change their political party affiliations.

I think this fits Specter pretty well. We’re not in a realignment, but clearly there has been a secular rightward shift in the ideological location of the Republican Party. Moreover, there is a large legislative agenda that would continually force Specter to confront his ideological discomfort. Add to that the electoral challenges of running in a closed primary, and, more generally, the challenges of being an elected Republican in a state trending Democratic.

(Also: a list of party switchers in the Senate is here. Wikipedia is also quite good.)

{ 3 comments }

Jason M April 28, 2009 at 5:45 pm

King and Benjamin’s research would be news to Chris Matthews who just declared that there’s no such thing as political science; politics is an art and the Specter switch proves it b/c it was unpredictable. His guests readily agreed. Thanks for posting this as a response (even if you hadn’t seen the Matthews clip).

Chris April 28, 2009 at 6:27 pm

There’s another piece that is relevant to the Specter switch. Specter negotiated with the Democrats to retain his seniority and is leaping ahead of Tom Harkin for chair of an appropriations subcommittee.

Antoine Yoshinaka, “House Party Switchers and Committee Assignments: Who Gets “What, When, How?””, Legislative Studies Quarterly XXX:391-406

Abstract: What are the political consequences for members of Congress who switch parties? Roll-call and electoral consequences of congressional party switching have been studied, but other implications of party defections have yet to be systematically explored. In this article, I examine the committee assignments of House party switchers and argue that party leaders seek to reward members of the opposing party who join their ranks. Using committee assignment data from the 94th House (1975–76) through the 107th House (2001–02), I show that party switchers are more likely than nonswitchers to be the beneficiaries of violations of the seniority norm. The findings from this article are of interest to students of political parties and legislative institutions, and fill a gap in the literature on party switching.

Andrew April 28, 2009 at 9:49 pm

These are really, really nice graphs. My only complaint–you knew I had to have something to say here–is that there’s something weird going on with the x-axis. Either “1995″ and “1997″ should really be “1996″ and “1998″ or there’s something funny going on.

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