(Well ok, "chairmen" are just called "chairs" now because some of them are women, but whatever; shouldn't it be "chairpersons"?)
Anyway, Jay Cost has written a terrific explanation for why Democrats in Congress can't pass bills despite their commanding majority: their committee chairmen are far more leftist than the median Congressional Democrat.
From 1954 to 1970, there was generally a tight correspondence between the committee chairs and the median legislator, with each being pretty moderate. In the mid-70s, they all tacked to the left - but whereas the median legislator quickly swung back to the right, the chairs kept trending leftward. By the 103rd Congress (1993-94), the differences had become quite substantial - with committee chairs being well to the left of the median legislator. After 12 years of Republican rule, the Democrats returned to power - and their chairs had moved farther leftward while the median voter was basically unchanged. The 110th Congress (2006-07) exhibits the largest divergence between the chairs and the median legislator since World War II. We don't yet have ideological scores for the current Congress, but I am sure there is still a great deal of space between these groups.
Much of this deviation can be explained by the system of seniority that governs chairmanships. It's not a formal rule among House Democrats, but nevertheless:[Nancy] Pelosi, unlike her GOP predecessors, chose to follow seniority in designating committee chairs. As a result, many of the Democratic chairs are liberal "old bulls" who either headed or were senior members of several of the most influential committees prior to the GOP takeover in 1995. [Davidson, Oleszek, and Lee (2008), 213.]
I mentioned last week that Bush's median share of the 2004 vote in the districts of current chairmen was just 36%. Democrats in liberal districts are less likely to be defeated, meaning that they are around long enough to ascend to chairmanships, and more likely to be liberal.
Meanwhile, thanks to majority-minority districting, as well as the party's overwhelming strength in densely populated urban areas, Democrats win 80-90% of the presidential vote in many congressional districts, which means they are quite safe. But it also means that to find 218 seats, they have to carry districts where their presidential candidates win less than 50%. Thus, you get a phenomenon like the current one: Heath Shuler (D-NC) and Stephanie Herseth Sandlin (D-SD) make the difference between majority and minority status, but Charlie Rangel (D-NY) and Barney Frank (D-MA) gavel the key committees once the majority has been achieved.
Representatives like Shuler and Herseth gave the Democrats their majority, but because of their lack of seniority (due to the lack of security of their seats) they don't have much influence in the House. It's no surprise that these chairmen craft leftist bills that the Representatives their majority depends on cannot vote for.
Side note: that "fringe" party members have little effect on policy is generally an under-appreciated benefit of the two-party system. Many multi-party parliamentary systems end up seating tiny delegations from the, e.g., Communist or Nazi parties which, despite their minuscule sizes, end up being instrumental in breaking ties when the larger parties disagree.
(HT: The Corner.)