Schumer was talking about this yesterday, and listed certain defectors as McCain and Chaffee. The other possibilities will probably be negotiated in backroom deals. Snowe, Collins and Specter are all possibly to likely opposed to application of the Constitution, preferring instead the collegiality that can only come from being an elitist.
Specter will be on board for this vote. This was the price he paid for garnering the Judiciary chairmanship with his colleagues.
This is just noise to paper-over his "difficult" vote with our side.