Larry Sabato explains why. Money quote:
We continue to believe that President Bush absolutely, positively MUST have at least a 51 percent approval rating in the nation as a whole to be reelected. Second, given our surmise that the undecideds/leaners will break somewhat more heavily for Kerry, we think Bush needs to have built a lead of at least several points overall to win narrowly. In other words, a polling tie probably results in Kerry’s election.
Then add in the massive new registration numbers in Democratic constituencies. Tonight’s debate is obviously critical for momentum in the home-stretch. Check in for post-debate reactions tonight.
The Dish 