A reality McCain might as well consider.
No matter who is elected President, they will be facing a Democratic Congress. McCain can promise all he wants, and he's going to have a hard time delivering. Under one condition.
That Pelosi and Reid are replaced with people who are not in complete awe of a Republican President. I have the impression they wet their pants when Bush sends a message, and do worse in person. Americans didn't elect a Democratic Congress in order to have those two people sabotage their interests.