Peter, the general rule is as Jonah stated. It is based on the belief that undecided voters are generally voters who are dissatisfied with the incumbent – with whom they are already familiar – and waiting to be persuaded by the challenger – whom they know less well.

For that reason, and because the most encouraging poll question for Kerry has been the “wrong direction” numbers, his campaign has been trying to make people feel more comfortable with him, and it appears he made some progress in that direction during the debates.

But according to the pollsters I’ve spoken with, at this point, with millions of dollars spent on ads, and the conventions and the debates over, very few undecideds still have little or no impression oe who Kerry is and what he stands for (or doesn’t). Which means it’s harder to predict how undecideds will break.

Expect both campaigns to try hard in the final days to drive up the opponent’s unfavorables – which has been going on for a long time anyway. But there are ways to plant doubts in voters minds at the last minute (recall the 2000 DWI charges against Bush).