...and this is one of those times: Unprincipled Hack (D-PA).
Now, I have often defended Specter to some of my fellow conservatives. I said repeatedly that it takes a certain amount of courage to remain a Republican in a state like Pennsylvania. I defended him saying that we still had his vote on fiscal issues (I was wrong). I defended his stance on judicial matters, too.
I would have defended him if he had chosen to become an independent like Lieberman. This is, however, entirely different. As Jonathan Chait puts it: "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."
Specter now needs to win a Democrat primary. If he is to have any hope of winning it - after all, he has no built-in machine within Democrat politics per se - he is going to have to move more consistently left. I hope he doesn't, but I don't see a whole lot of sense in hoping at this point.