Sen. Olympia Snowe, R-Maine, is the latest politician to cite congressional paralysis as the reason for her retirement. As politics has gotten more polarized, the ranks of the centrists have thinned out. The ones left have become less powerful.
"People would ask me do you think things are going to change," Snowe said. "And I wasn't sure it would change."
With the Senate tied in knots over even minor measures, Snowe decided to take her talents elsewhere.
Was it just too lonely to be a moderate Republican in the Senate?
"Well, there wasn't a lot of company, that's for sure," Snowe said.
Most of her fellow moderates have either moved to the right, or retired. Moderate Democrat Evan Bayh cited gridlock when he left the Senate in 2010.
Sen. Joe Lieberman, I-Conn., is retiring at the end of the year. "I feel Olympia's pain," he said. "People are sort of pulled apart by this process."
Sen. Claire McCaskill, D-Mo., said, "The problem now is the two ends are getting all of the amplification. The political system loves the extremes. It doesn't so much show a lot of love for the moderates. So it's really hard right now."(At left, watch more from Sen. McCaskill.)
In the House, 22 of the 54 centrist Democrats known as "Blue Dogs" were defeated in the last election.
To some degree, it's a reflection of the electorate. According to Gallup, the percentage of Americans who consider themselves moderate has dropped from 43 percent to 35 percent over the past 20 years.
But Jeff Bell, former aid to President Ronald Reagan, says polarization can actually be helpful - to a point. "It's ugly. It's messy. But I think there are times in history when it's better than the alternative which is everybody getting along on behalf of something that isn't that good."
After 33 years in Congress, Snowe says she really hasn't thought about what she'll do next.
Did she make the right decision?
"I'll never know," she said. "I think I made the right one, but I'll miss it. I'll miss it."
Her Republican colleagues will miss her, even if she bucked her party from time to time. Snowe was a favorite to win reelection in November. Now Republicans are going to have to struggle to hold on to her seat in Maine. That makes their goal of regaining control of the Senate that much more difficult.