When a politician switches parties, it’s customary for the party he’s abandoned to denounce him as an unprincipled hack, and the party he’s joined to praise him as a brave convert who’s genuinely seen the light. But I think it’s pretty clear that Specter is an unprincipled hack. If his best odds of keeping his Senate seat lay in joining the Communist party, he’d probably do that.

To be sure, Specter is a real moderate on some issues, but his contortions are so comical that no principled read on his actions is very plausible. Specter favored the Employee Free Choice Act favored by labor, turned against it when he faced a primary challenge, and then abandoned his party altogether when it became clear he couldn’t win his primary. In the meantime, he came out in favor of a Hooverite spending freeze after backing the stimulus bill.

A couple quick thoughts on what this means for the parties. Obviously, it’s a disaster for the Republicans. Pat Toomey’s primary challenge to Specter was a gamble for Republicans. The best-case scenario would be to force Specter to move to the right without actually beating him. It actually seemed to pay off when Specter flip-flopped on EFCA, a crucial piece of legislation that’s worth risking a Senate seat over. But now it’s blown up in their faces completely. Specter says he’ll still oppose EFCA, but I have trouble seeing him really maintain that stance. He has to make it through a Democratic primary now. That’s very hard to do in Pennsylvania when the AFL-CIO is out for your blood.

Specter’s most likely play is to stay formally opposed to EFCA, but support a compromise along the lines of what some moderate Democrats might favor. He certainly can’t risk being the decisive anti-EFCA vote. Democrats in the Senate may be offering him institutional support in the primary, but primaries tend to be low-turnout operations, and Specter is going to have to work his way into the favor of the partisan Democratic base. Think of it this way: If you were a liberal (or pro-labor) Pennsylvania Democrat, would you vote for Specter? I wouldn’t. I’d be glad he left the GOP, but once he’s done that, he doesn’t have anything special to offer. He’d be a nearly unbeatable general election Senate candidate against Pat Toomey, but a standard issue Democrat could probably do well, too.

The broader symbolism here is that it’s another sign that Barack Obama’s first two years may not look like Bill Clinton’s. In 1993-94, Clinton’s approval ratings sagged, his party lost special elections everywhere, and conservative Democrats were switching to the GOP. Obama’s approval ratings are high and holding steady, Democrats remain far more popular than Republicans, Democrats held the first special election, and now they’ve picked up a party switch. It’s still early, but Obama is starting to build a self-sustaining psychology of success.

--Jonathan Chait