Vermont Senator Jim Jeffords (I), who became a liberal hero when he defected from the GOP in 2001, is retiring from the Senate after the conclusion of his term in 2006. Many thanks to a dedicated public servant.
More interesting is CNN's claim that the state's sole Representative, Bernie Sanders (I), is going to run with Jeffords out of the race. Sanders is quite popular in Vermont. He also happens to be a member of the Democratic Socialists of America (not affiliated with the Democratic party in any way whatsoever). If Sanders wins (and he very much could), this would make him the first openly socialist senator in, well, in my recollection of American history.
UPDATE: I'm not really sure who believes otherwise, but The Moderate Voice assures us that Jeffords really is retiring for health reasons, not because he's politically vulnerable.