With this week’s announcement by Sen. Olympia Snowe, R-Maine, prospects of a more united Congress grew a shade darker. Snowe’s plan to retire at the end of this year brings the casualty count this Congress for Senators widely seen as moderates to three – Snowe, Sen. Ben Nelson, D-Neb., and Sen. Joe Lieberman, I-Conn. And the situation looks just as, if not more, worrisome in the House.

Add to this the announced retirements of Blue Dog Democrats, a group known for moderate positioning, Rep. Heath Shuler, D-NC, and Rep. Dennis Cardoza, D-CA, as well as uphill battles for many moderate Republicans and Democrats around the country facing difficult reelection bids, and next year may bring an even more polarized legislature. While 2010 losses for moderates were heavily the result of the ever-changing sway of voter opinion, 2012 losses for this crowd will more likely be a factor of recent highly-partisan redistricting.

In 2010, moderate Democrats were swept almost en masse from the House due to their vulnerability in swing districts and blowback from discontent electorates. But in that election, moderate Republicans – such as Charles Bass, R-N.H., and Michael Grimm, R-N.Y., both members of the moderate Republican Main Street Partnership – often replaced moderate Democrats. With this in mind, it seems the results of these elections did not, overall, so drastically alter centrist numbers because Republican victors in moderate districts answer to the same moderate voting population as their predecessors. And, as many new moderate members have demonstrated in their statements and votes over the last Congress, they are aware of this precarious position.

The House elections this fall, however, will be a much different story. For many states around the country, the popular trend in recent redistricting plans has been to toss out swing districts in favor of safe seats in newly-carved maps that will offer much more certainty from the November polls. While some states have been forced to redraw overly-partisan maps, others will likely be defined by clearly-divided delegations next year.

This may provide stability in the number of Representatives from each party, but it undercuts attempts made by moderates to bridge the partisan divide – a necessity for getting things done in a politically divided government. In swing districts, reaching across the aisle shows a willingness to negotiate with the other side which, in such districts, aligns politically with about half the constituency.

So Representatives in moderate districts are motivated to do just this. Gaining support from the political base won’t be enough. To get the votes they need – including from conservatives and independents – moderates have to work effectively with the other side of the aisle or at least give the impression that they are.

Without split-electorate districts, the motivation for working across the aisle is gone. In fact, in partisan districts, a candidate’s base, which wholly decides the election, is more likely to see this as a betrayal to the party and meaningful pursuits of bipartisanship put a candidate at risk in the primary phase. In moderate districts, there still may be a tendency for some primary voters to take their grievances to the polls, but for the most part, these voters will get behind someone they think has a chance in the general – typically the candidate that can pull votes from the other side.

Although most Americans rally around the idea of bipartisanship, it is a difficult pursuit for elected officials in partisan districts. Voters want dialogue and negotiation, but only if the other side is making the compromise.  In moderate districts, however, there is a different dynamic that allows and encourages this sort of crossing the divide.

If the latest blow to moderate sensibilities, Snowe’s retirement, is of concern, then the fallout from November’s elections may be nothing less than disastrous for the political center. As moderate districts become a dying breed, so too will the types of Members that used to represent them.

Related posts:

1. Some Suggestions for Improving Congress
2. Overcoming Foreign-Policy Disunity
3. Civil Discourse and the Clash of Ideas
4. Lee Hamilton: First, Let’s All Be Americans
5. For Political Closure, We Need Disclosure