McCain wants the war to go well so that we can stay in Iraq forever.
Obama wants the war to go well so that we can bring our troops home.
As Josh says:
We have two candidates with starkly different positions. Barack Obama is for an orderly and considered withdrawal of all US combat forces in Iraq, a process he says he will begin immediately upon taking office. John McCain supports a permanent garrisoning of US troops on military bases in Iraq -- a long-term 'presence' which he hopes will require a constantly-diminishing amount of actual combat and thus an ever-diminishing toll in American lives.
This is, I believe, a fair and even generous description of each candidate's essential position. And the recital makes the key point clear: McCain's position is squarely on the wrong side of public opinion -- in fact, to an overwhelming degree.
This is why the McCain campaign spends what seems almost literally to be all its time (with tractable reporters in tow) scrutinizing the rhetorical entrails of Obama's every statement trying to find some movement or contradiction or frankly anything that can be talked about to keep everybody's attention (press, commentators, citizens, precocious teenagers) off the fact that McCain's position on Iraq is wildly unpopular and even more what McCain's position actually is.