In a very interesting moment at his press conference today, Arlen Specter showed that he remains in many ways a small-c conservative -- it's just that he's not a complete and utter right-winger.
Specter railed against his former compatriots in the Republican Party for not supporting moderates, and being in the thrall of the Club For Growth, the right-wing group that was working to defeat him in the 2010 primary:
Republicans didn't rally to Wayne Gilchrest in Maryland -- he was beaten by the Club For Growth and the far right -- and lost the general election. Republicans didn't rally to the banner of Joe Schwarz in Michigan -- he was beaten by a conservative and the Club For Growth -- and they lost the general election. Republicans didn't rally to Heather Wilson in New Mexico last year, and she was beaten in a primary, and lost in the general election. The Club For Growth challenged Linc Chafee -- remember Linc Chafee? -- they made him spend all his money in the primary, and he lost the general. And had Linc Chafee been elected in 2006, the Republicans would have controlled the Senate in 2007 and '8, and I would have been chairman of a committee.
He later added:
And for the people who are Republicans, to sit by and allow them to continue to dominate the party after they beat Chafee, cost us Republican control of the Senate, and cost us 34 federal judges, there oughtta be a rebellion. There oughtta be an uprising.
So Specter's problem wasn't that he's not a conservative, but that he's not conservative enough for a shrinking GOP. And if he's not a complete right-winger, his only real choice is to be a Democrat.
And that's where politics seems to be right now: The right-wing nuts versus everyone else. Specter is on the more conservative end of the "everyone else" category, but being a Democrat now offers him more chance for political success (and sane, rational discourse) than the other option.