Just to follow up on Chait's smart thoughts about the uphill battle Specter could face in a Pennsylvania Democratic primary, you have to imagine this statement from Joe Lieberman isn't going to help Specter with the people who'll be voting in that primary:

I enthusiastically welcome my good friend Arlen Specter into the Democratic caucus. It will be very good to have the company of yet another independent minded Democrat in the caucus!

Gotta love the exclamation point, just in case Atrios's head hadn't already exploded.

--Jason Zengerle