If McCain could successfully use his influence to assure Scalia-like originalist judges and break any filibuster the Democrats might propose, he might just be on his way to becoming the Republican nominee in 2008. That is the one thing that could make the base forget about some of betrayals in the past.
McCain is the one who sabotaged the end of the filibuster that would have guarenteed constitutionalists on the Court because he didn't want his competitors for the nomination to get credit (Frist, Allen) after he foolishly put it out there he'd vote no, and couldn't take it back without losing face.
he won't win back the base with this blatant ploy, since he is the reason we're in this mess now rather than had it settled a couple months ago.
I'm willing to use him, but I don't trust him, and his motives are purely selfish.