The big problem here is that he will need Obama’s support to win reelection as a Democrat. Obama will extract whatever quid pro quo he wants in exchange for his support. My guess is that Specter becomes a fairly reliable Democratic vote in short order. He will be allowed to break from the group occasionally – enough to keep his “independent” cloak safe – but on any and every really serious proposal (card check, health care, FOCA, any big budget bills) he’s a safe Democrat vote now. It’s the price he’s paid for one more term in congress.