It has been suggested that if McCain is president, the Republicans in Congress will just go along with anything he wants, because he is a fellow Republican. That could be true.
But what if those Republicans are paying attention to what is going on with their base? There is angst, to put it mildly. The smart ones could use it as an opportunity to oppose McCain if his policies start tilting to the left. The more vehemently they oppose him, the more their conservative base will adore them. They could even pick up Independent and (gasp) Democratic voters because they would be seen as the mavericks. Could it happen? I don't know, but it sure would be interesting.