That Obama is set to nominate so many former legislators to his Cabinet and senior White House staff provides a rare opportunity for comparing the ideological make-up of the new administration to that of Congress.

With the nomination of Hilda Solis to be Labor Secretary and Ray LaHood to be Transportation Secretary, there will be six former House and Senate members in the cabinet (including Clinton, Daschle, Salazar, and Richardson). Throw in Obama himself, Joe Biden, and Rahm Emanuel, we have a pretty good sample of former legislators to compare to the current composition House and Senate Democratic caucuses.

To gauge the differences between the administration and Congressional democrats, I use Keith Poole’s “common space” measurement of conservatism. This measure is an adjustment of DW-NOMINATE scores designed to facilitate comparison of the House and Senate. Each legislator is given a single conservatism score for her entire career ranging from around -1 (very liberal) to 1 (very conservative). One drawback is that these scores are only available up through the 109^th Congress (2005-2006). So I can only compare the cabinet to the Democratic caucuses of that term. Another is that Bill Richardson’s score more than a decade old (but the rest continued to serve through the 110^th Congress).

The following table list the conservatism scores for the administration as well as the House and Senate leaders and the medians of the caucuses.

The evidence is pretty strong that the administration lies considerably to the right of the Democrats in the House, but is reasonably representative of Senate Democrats. But only Solis comes from the most liberal wing of the party. The center of the party is well represented in powerful positions by the president, vice-president, secretary of state, and WH chief of staff while the lower cabinet is filled with more moderate Democrats and a Republican. No wonder Nancy Pelosi is worried about being triangulated.

Of course, maybe the table is misleading because it only includes cabinet-designates who served in Congress. Maybe liberals and progressives are better represented in the other positions. Doubtful. Gates is a Republican. Teachers unions were disappointed with Duncan. Geitner is a Robert Rubin/Larry Summers protégé. Napolitano and Vilsack are red state governors. Shinseki is a hero to the left, but probably not of the left. Donovan appears to be a centrist who worked in both the Clinton and Bloomberg administrations. Holder is a corporate lawyer. So think I that leaves Stephen Chu as the only remaining cabinet member with views consonant with the progressive wing of the Democratic party.

There has been a fair amount of grumbling just below the surface about how poorly progressives have fared. Rick Warren’s invitation didn’t help matters. It will be interesting to see how long Obama can keep the lid on it before it boils over.