Pulling Apart

GRAPHIC: Senate Centrists in Decline

INTERACTIVE GRAPHIC: 2010 Vote Ratings

GALLERY: Most Conservative Members Of Congress

GALLERY: Most Liberal Members Of Congress

Those pairings underscore another striking trend in the Senate results: the convergence among the ratings of senators from the same party who represent the same state. Although the gap between senators from opposite parties who hail from the same state (say Democrat Tom Harkin and Republican Chuck Grassley of Iowa) remains large, partisan pairs increasingly follow the same course. For instance, Democrats Carl Levin and Debbie Stabenow of Michigan and Barbara Mikulski and Ben Cardin of Maryland all tied for the most liberal ranking (as did Democrat Patrick Leahy and independent Bernie Sanders of Vermont). The other end of the ideological scale finds the overlap between Tester and Baucus, Webb and Warner, Bennet and Udall. Similar patterns are evident among Republicans. In all, 22 states were represented by senators whose vote ratings were within 5 percentage points of each other. In only 12 states did senators have vote ratings more than 25 percentage points apart.

This convergence may illustrate the diminished ability of senators to sail a distinct course, independent of the dominant political currents in their state. The frequent pairings suggest that senators are aligning more closely with their state’s underlying political balance, or at least the consensus in their party within their state.

Those who break from that consensus face an increasing risk of primaries driven by activists of the Left or Right; three senators—two Republicans and one Democrat—were denied renomination in 2010, almost as many as in the previous 26 years combined. “There is more of a demand in each party for a degree of purity or inflexibility that was not there before,” says Danforth, now a lawyer in St. Louis. Lott notes that the growing threat of such primary challenges (at least three more Senate Republicans could face serious opponents in 2012) powerfully reinforces the trend toward partisan and ideological conformity evident in the ratings. “You really need to toe the line,” he says. “That affects people’s thinking—both Democrats and Republicans.”

A TALE OF TWO PARTIES

In the House, as in the Senate, Republicans pursued a more unified course in 2010 than Democrats did. The contrast between the parties was arguably even greater in the lower chamber. What’s more, many House Republicans compiled conservative voting records regardless of the demographic or political bent of their districts, while Democrats differed substantially based on those factors.

Among Democrats, for instance, there was a clear relationship between their 2010 vote rating and the way their district voted for president in 2008. The 124 House Democrats representing districts where Obama won at least 60 percent of the vote compiled an average liberal score of nearly 81, well above the party average of 70. In stair-step fashion, the average liberal score dropped to 69 for the 48 House Democrats in districts where Obama won between 55 and 59 percent, and to 63 for the 35 in districts that he carried with less than 55 percent of the vote. Most strikingly, the average liberal score of the 47 House Democrats from districts that McCain carried in 2008 stood at just 50—fully 30 percentage points below the number for those holding the safest seats. Of the 50 House Democrats with the most-conservative voting records, 35 were from districts that McCain carried.

“There is no question that the middle in the Senate has shrunk considerably.” —Former Senate Majority Leader Trent Lott

Among Republicans, the variation was much smaller. The 52 House Republicans from districts where McCain won at least 60 percent of the vote produced an average conservative score of nearly 83. The 33 members from districts where he won between 55 and 59 percent generated a slightly more conservative ranking of 84, and the number fell only slightly, to 78, among the 54 lawmakers in districts that McCain won with less than 55 percent of the vote. Even the 34 House Republicans from districts that Obama carried compiled an average conservative score of 72—only about 10 percentage points less than those from the safest seats.

The story is similar when looking at the House through a demographic lens. In 2009, National Journal divided the chamber into four quadrants based on whether the share of the white population with college degrees exceeded the 30.4 percent national average, and whether the district’s minority population exceeded 30 percent, the level that an earlier NJ analysis found to be a revealing dividing line in election results. (See “The Four Quadrants of Congress,” NJ, 2/6/10, p. 20.)

In 2010, as in earlier years, House Democrats from districts high in both diversity and education posted much more liberal scores than those from districts low on both measures: the predominantly blue-collar small-town and rural seats represented largely by members of the Democratic Blue Dog coalition. Democrats from the “high-high” districts posted an average liberal score of 79, compared with an average liberal score of 62 for those from the “low-low” districts. In stark contrast, the 84 House Republicans from low-low districts posted the exact same 79.6 average conservative rating as the 30 Republicans representing districts high in diversity and education.