The political scientists Jeff Lewis (UCLA) and Keith Poole (UCSD) have estimated the spatial locations (essentially, the ideological positions) of members of the House in the 109th and 110th Congress in order to analyze the vote on Iraq withdrawal in the House on Friday. As it turns out, supporters and opponents separated almost perfectly along party lines, with only a handful of leftist Democrats and conservative Democrats breaking ranks (plus two Republicans). Here’s how they summarize it:

[P]lacing a cutting point between Cramer D-AL and Boren D-OK correctly classifies all but 15 members for a correct classification of 96.5 percent [(430-15)/430] with a proportional reduction in error (PRE) of .929 [(212-15)/212]. The vote was highly ideological. All newly elected Democrats voted YES and all newly elected Republicans voted NO. In addition, note the cluster of voting “errors” at the furthest left rank positions. These were Democrats who voted NO because the Bill did not go far enough to end the Iraq War. This is a rare example of “two-ends-against-the-middle” voting (technically, the roll call had three outcomes!).