I'm thinking (and hoping) Kerry.
I remember the last election. I didn't vote, because I didn't like this country enough to vote, to be blunt. I didn't see my being involved with the political process as something that would be important to me at all. Almost everyone I talked to was anti-Bush, with a few exceptions. This was in PA, in the Haverford (main line) area, where I would have expected a lot of staunch Bush supporters (it's one of the richest, if not the richest, neighbourhood in the country).
Bush still won (apparently). The election seems like it was too close to call, even now, with controversy over who actually "won".
Since I'm assuming the overwhelming majority who voted for Bush will vote for him again, and those who voted against will do the same, that means this election is going to be as close. The only deciding factor seems to be new voter recruitment. And the Democrats, by all counts, seem to have done a much better job. They had it easy, because almost all of those people I knew who were anti-Bush did NOT vote...they were mostly college kids. It simply doesn't take much to get those people to switch from "i can't be bothered to vote, who cares" to "i'm voting this time" because most of them already WERE strongly anti-Bush to begin with, and seeing him elected did 90% of the job of convincing most of those college kids to vote.
Bush, on the other hand, has a harder job. I think what it boils down to is that there was a huge population of non-voters in the last election who were, either vaguely or definitely, anti-Bush. There were a few, no doubt, who were pro-Bush. When everyone's deciding to vote this time around, no matter what, this gives Kerry a big advantage. A few new voters might vote Bush after suitable kicks in the pants from their Churches, but I think the numbers are on Kerry's side this time around.
It'd be terrible if I'm wrong, of course, so I hope I don't have to eat my words.
-Dave.