If the nomination is defeated and President Bush picks a stellar nominee, he will redeem himself and reinvigorate his presidency.
Will pacifying the base ... which aside from this has been pretty much behind him through thick and thin ... actually give him any more capital with the people who get to vote on this, i.e. the U.S. Senate? That's the problem, we can holler until we're hoarse, but we still don't get a vote on this nomination. We can certainly say that by voting for the president, we expressed our desire as to what kind of SCOTUS justices he would appoint, we can threaten to bug out of the next election and stop contributing to the party, but it doesn't change the fact that being that this is a republic and not a democracy, he gets to pick and the Senate gets to vote.