I think shortly after he takes office either Iran or Israel will attack the other.
This is if Bush hasn’t already attacked Iran.
Iran will attack once they feel negotiations with him have gone well enough to lull him into a sense of safety. Or sooner if they feel the US is not prepared to respond quickly due to the leadership change.
Israel will attack once they believe the U.S. will not preempt the nuclear proliferation of Iran.
If this does occur the removing of troops from Iraq will be put off long term.
Of course if McCain is elected I think the same thing is going to happen. Except for the negotiations part.
Though even if this doesn’t happen, I agree with trainerboy.