Most Senators Leaving Since 1996 May Polarize Chamber

Retirement announcements by Senator Olympia Snowe and other centrists are putting more U.S. Senate seats at stake than at any time since 1996 -- and the result may be an even more polarized environment next year.

Snowe, a three-term Maine Republican known for voting with Democrats on some high-profile issues, said her decision was driven by frustration over partisanship and lack of compromise in the Senate. Other departing senators who seek consensus on such issues as debt reduction say they share her view.