I've long thought (although I admit that at times certain circumstances have had me waver a bit) that this country will not elect an anti-war President in a time of war. I agree with John Fund here that McCain may have a better chance against either Clinton or Obama than many give him credit for.
I have a nagging concern on what a post-election Democrat Party will look like should McCain win. Not long after 9/11...probably due to the closeness of Bush's win in 2000 and certainly after the Republicans increased their majority in 2002, the Democrats' public face showed that they had simply lost their minds. They embraced, then ceded their foreign policy agenda to a woman who is a simple fool. They held on to her until after her 15 minutes of fame were gone. They tolerated shrill harpies who are capable of taking the most vile of positions. Their lions were unable to take a calm rational argument to the public.
However, maybe the face of the Democrats was not insane, but something they cynically used to oppose the Republicans. Early on, Democrat David Obey knew that they did not have the votes to support a proposal to defund the war. Yet, they spent the entire year after they attained the majority doing nothing except to do exactly this. And when President Bush adopted Gen Petraeus' Surge, did the Democrats even allow that this approach might yield the desired results? No. They (or more correctly, their mouthpieces) questioned the General's patriotism. And after the Surge had had it's time in the field, did the Democrats even state the obvious: that it was actually working? No. The Rolling Stone now has a name for them: Chicken Doves...those Democrats who took an anti-war stance, not as a true measure of their commitment to ending the war, but to use as a tool to club the Republicans and Bush with.
So what will happen if Obama wins the popular vote, but Clinton takes the nomination through her strength with the super delegates? What will happen if McCain wins? What will happen if either Democrat wins, and then decides that we cannot leave Iraq? Will the Democratic faithful take to the streets (again)? Can the leadership rein in their extreme edges to be able to actually accomplish an agenda?
As much as I think it will be a disaster for either Clinton or Obama to win the Presidency, I don't think that a McCain win will be easy. Over the last 7 years, the Democrats haven't shown that they're able to do much other than attempt to obstruct.