Candidate pool for Congress is missing moderates, study finds

Everyone knows that Congress is politically polarized, but why? One promising place to look for an answer is state legislatures, where fewer moderates, it turns out, are opting to run for higher office.

That's the chief takeaway of a study released Wednesday from Duke University. Upon tracking 569 legislators between 2000 and 2010, a researcher found that those in the “ideological middle” of state chambers are much less likely than their peers at the ideological poles to make a run for a US House or US Senate seat.

This trend, experts say, is both a cause and a consequence of America’s fractured politics – a kind of self-perpetuating cycle.

“This is a mechanism for how polarization has been exacerbated and reinforced,” says report author Danielle Thomsen, a post-doctoral fellow at Duke University in Durham, N.C. “The process of polarization had begun to occur before this study started. What I am saying is that these patterns of self-selection – given that these people are in the congressional pipeline – is one mechanism by which polarization has worsened.”

These findings add another piece in the puzzle of the rise of national partisanship. Recent studies have found that today's sharply partisan Congress stems from the gradual replacement of moderate members with officials whose views are more one-sided, rather than from shifting views of existing legislators.

The Duke report found that Republican state legislators whose views resemble those held by conservatives in the party, such as Rep. Paul Ryan (R) of Wisconsin, are more than nine times as likely to run for Congress than are relatively liberal Republicans whose views align with moderate legislators, such as former Sen. Olympia Snowe (R) of Maine. Of the legislators surveyed, 1.9 percent of conservative Republicans ran for Congress, versus 0.2 percent of moderates in the party. 

Among Democrats, this disparity was less pronounced but still significant.

A Democratic state legislator whose views align with those of a reliable liberal, such as Nancy Pelosi (D) of California, is at least five times as likely to run for congressional office than is a representative whose views are considered moderate among congressional Democrats.

Why are so many centrists reticent to run? Well, Duke's Ms. Thomsen has several theories.

“A lot of it is probably attributed to the fact that [moderate state legislators] can’t get past the primary, or win the general," she says. "But there’s more to it than that: When they look at the national environment, they see they’d have a hard time effecting desired policy changes or getting an influential position.”

Thomsen notes that “you have to give up something” to run. But, given the divided national political climate, moderates stand to gain little from this sacrifice.

She also cites fundraising challenges as a potential factor. Activists at the political poles are generally more fired up than those in the middle and are more willing to donate to campaigns, she says. 

Another cause could be the perceived effect of gerrymandering of congressional districts to make them "safe" for one party or another. Most political scientists don't put much stock in that explanation given that politics are becoming as polarized in the US Senate (which are statewide races) as in the House, Thomsen says. Still, state legislators may mistakenly believe that the political redrawing of districts may make a moderate campaign impossible, she suggests.

The study also showed that gap between moderate and hardcore state lawmakers when it comes to running for Congress exists everywhere in the nation, regardless of an area’s politics.

“The actuality is that moderates aren’t really running anywhere,” Thomsen says. “It doesn’t matter if it’s in Oklahoma’s Second District, [which leans right, but has a history of electing conservative Democrats,] or California’s [liberal] Ninth District.”

Thomsen’s findings come amid a historic period of partisanship in Congress. According to a Pew report in June, no Republicans in the House or Senate are more liberal than the most conservative Democrat, nor are any Democrats more conservative than the most liberal Republican.

Twenty years ago, 12 legislators occupied this middle ground.