All these graphs plus large format poster-size extras are available in high resolution .pdf format here.
National Journal released their 2006 liberal-conservative roll call scores for the House and Senate last week. The National Journal report of these scores is here. National Journal's scores are interesting because they calculate separate scores for economic, social and foreign policy dimensions, plus overall scores. They also use more roll calls in each issue area than most interest groups use in their "support scores". NJ uses 30-40 roll calls each for economic and social, and 17 or 18 votes for foreign policy. That compares to as few as 10 in the typical interest group rating.
By all means go to National Journal's site for the scores of individual members and for NJ's write reports on these results. They make it easy to find individuals or to look at the entire range of scores. Plus the reporting by Richard Cohen here is a good read.
I've used "Conservatism" score here. The NJ's liberalism score is 100-Conservatism, so the scores are mirror images of each other. (This is not exactly true of the three components, but they are near-mirrors so I only use the conservative score there as well.) Using this measure makes ideology score run left-to-right as it should for the graphs.
There are 44 Democratic Senators rated for 2006. Jay Rockefeller (WV) missed more than half the votes on social issues and was therefore excluded by National Journal from the overall rating (his conservatism scores were 37 and 39 on economic and foreign issues, which would put him near Blanche Lincoln (AR), who is the 5th most conservative Democrat.)
Members of the 109th Congress who did not return to the 110th are marked with an asterisk (*).
The top two plots show the Senate parties. The location of presidential hopefuls will be of interest, as will that of Joe Lieberman (9th most conservative among Dems) followed by a not-so-distant Hillary Clinton at 13th most conservative (32nd most liberal), only 4 spots to the left of Lieberman. By contrast Barack Obama ranks as the 10th most liberal Democrat (35th most conservative). The other two current Senators are Chris Dodd (CT) at 17th most liberal (28th most conservative) and Joe Biden (DE) at 24th most liberal (21st most conservative).
On the Republican side, John McCain (AZ) earns his moderate image by scoring as the 46th most conservative of 55 Republicans. Sam Brownback (KS) is 35th and Chuck Hagel (NE) is 29th.
If we look at the three subscales National Journal uses we find a couple of interesting things.
First, the three subscales are a bit more consistent with each other for Democrats than for Republicans. The red-Republican points the the three top left plots show relatively little relationship. The Democrats also show more scatter for the Foreign-Social relationship. This could be because the areas are not as ideologically integrated for Republicans as for Democrats, or it could be that the scaling is not that stable, even with 30 something votes. (Political scientists tend to use ALL non-unanimous roll calls for such scaling efforts, rather than just a few dozen. Those efforts have consistently found that roll calls fit a single dimension quite well, and do not require separate dimensions for social, economic or foreign policy domains. If that is right, then we might expect MORE relationship between these subscales than we see. Perhaps we'll get a look at this issue in some future analysis.)
It is interesting to note Sen. Joe Lieberman's positions in the plot above. The plots show quite well that Lieberman is unusual only on the foreign dimension, where his voting record makes him the most conservative Democrat (but among the 5 most liberal Republicans on the foreign policy domain.) On economic and social issues, he appears well within the range of Democratic senators and quite clearly to the left of all Republicans. This has serious implications for talk of a possible party switch. Unless his voting behavior changed, he would be the most liberal Republican by a fair margin.
For all the talk of bipartisanship, there is little ideological overlap of Senators.
Ben Nelson (NE) is by far the most conservative Democrat. But take him out (and with the defeat of Lincoln Chafee (RI) ) and there is literally no overlap between the parties' Senators. While the least conservative Republicans (Snowe, Collins, Specter, Coleman and Smith) have shown some willingness to vote with Democrats, and the most conservative Democrats (Nelson, Landrieu, Pryor, Nelson (FL)) sometimes cross party lines, there is less basis for ideological agreement than there was in the past when more members ideologies overlapped their party affiliations. Not that anyone really expects bipartisanship to break out anytime soon.
One other interesting result in the Senate plot is the line of "perfect" social conservative scores in the plot of the subscales above. Eighteen Republican Senators took the conservative position on social issues on every vote. But in the plot you can also see that this group varies quite a bit on the economic and foreign dimensions. While this group certainly defines the most conservative end of the Republican party, there is still a fair bit of variation in their overall conservatism scores, as seen below.
On the House side, with many more members, there is also a bit more partisan overlap, though less sign of bipartisanship.
The coherence of votes across policy domains (below) look about the same for the House as for the Senate. Again the Democrats appear somewhat more correlated across domains than do Republicans. Given the image of Republican unity in the House in the 109th Congress this remains a bit of a puzzle.
The entire House is plotted by party in the high resolution .pdf file here There are multiple plots for letter size paper plus oversized posters for all members of each party.
