I heard part of what Rush said about Specter today, he seemed to be quite forgiving about it (though he'd prefer someone else). I was really surprised. I agree, Rush is almost always right, and I greatly respect him and all he has to say. However, I have a negging little doubt about this particular thing. I'm thinking of Bush 41's appointment of David Souter... It does not pay to be soft regarding Supreme Court justices.
Bush 41 was not the conservative that Dubya is. Reagan is rumored to have said after the "no new taxes pledge" was broken that he should have gone with Ford (who of course appointed John Paul Stevens, possibly the most liberal justice ever). For that matter, if Reagan had been more diligent in finding a conservative instead of overzealously appointing the first woman justice, we wouldn't have the 4-4-1 split on matters like abortion we do today.
He's choosing party over principle, unless his first principle is "just win". Which it may well be.