Don't be afraid to pester the RNC, Senate Campaign Committee, Bush/Cheney Election Committee, etc...
If Bush really wants Specter relected he might strongly suggest that he compromise a little.
I would contact the prolife organizations in your state about Spectpr's intent to block the appointment of a prolife Arkansas district judge even though Arkansas' two Democrat senators support him. http://www.freerepublic.com/focus/f-news/1144839/posts
First, Specter distanced himself from Bush within 12 hours of winning the primary and he wouldn't have won without Bush. In his vitory speech, he reminded everyone that he was an independent voice and (using Bush's campaign ad wording) rubbed Bush's face in it.
Then days later Specter sided with the dems and voted against Bush's overtime pay bill.
Now, as you point out, he's standing in the way of one of his judicial nominees (Holmes).
Specter is not liked because he is so nasty, arrogant, and so hard to pin down. He has more weasel words than clinton. Any you deal that you make with him today will be broken tomorrow and he'll have you thinking that it was your fault.
He plays to his crowd. Everyone thinks that he is their best friend when he's pandering, er, I mean campaigning. And he is in perpetual campaign mode.
The only pressure that Specter feels is that which comes during an election from a conservative candidate. Now that he is facing a socialist, he beliefs that we don't have a choice but to vote for him. The most that we'll get from him now is lip service.