From this morning's LA Times , on Bush strategist Matthew Dowd:
It is an article of faith among political consultants in both parties that voters undecided late in a race trend against the incumbent. But given the conflicting impulses the polls find among these voters this year, Dowd predicted they would not break decisively for either Bush or Kerry. And many, he predicted, might not vote at all. In such a scenario, he said, turning out the party base would grow in importance.
Undecideds "might not vote at all". Why would Dowd say that, given that this has become one of the most highly engaged campaigns in recent memory? The real question is, under what conditions would undecideds stay home on election day?
Here's the answer, and Dowd knows it: if a negative campaign based on personal attacks were to confuse and disspirit voters, blur the lines between lies and the truth, and raise cognitive dissonance to levels of such discomfort that they just throw their hands up and abandon the whole process.
Of course, that strategy won't work with a candidate's most intense supporters, for whom loyalty is an article of faith. (And that applies to both sides.) Hence Dowd's reasoning.