Bill Maher did a great take-down of "undecided voters" recently (see BruinKid's recent diary). The real question is how to appeal to these people. They obviously don't care a whit about the actual issues because if they did, they wouldn't be undecided. They are typically vapid and shallow and want to appear to be principled with their "I vote for the candidate, not the party" BS.
As studies have shown, the more people actually learn about the issues and where the parties stand on those issues, the more likely they are to vote straight ticket. Voting "for the candidate, not the party" is an intellectually bankrupt position, it is not at all principled. But it betrays a sense of the importance placed on what others think of them. They want others to think they are principled rather than uninformed, which is what they actually are.
So rather than try to appeal to them on the issues, that they clearly care nothing about, I think it makes more sense to exploit the importance they place on others' perception of them.
Markos has hit this nail right on the head repeatedly and I only wish to emphasize what he has already said numerous times.
We need to make the case to these people that Obama is going to win and Romney is going to lose, and at this point the only unknown is the margin of Obama's victory. Pundits and political operatives on both sides have a vested interest in not revealing this information, despite the fact that they know it to be true. Pundits want to reinforce the horse race narrative of a neck-and-neck race because that's what keeps viewers and listeners tuning in. Once they admit the race is over, they lose their audience.
Operatives on Obama's side don't want their voters to become complacent while operatives on Romney's side want their voters to believe that Romney still has a chance to keep turnout on their side as high as possible. But when you look at polling analysts like Nate Silver or look at site like Intrade, it becomes clear that Obama is going to win and probably win big, and Romney is going to lose.
And here's the rhetorical question that they need to be asked, simply: do you want to be on the winning team or the losing team?