Nate Cohn at TNR:

[Recent] polling from Pew Research and NBC/WSJ suggests that Romney has a real problem with the undecided voters he’s counting on to put him over the top. Approximately half of undecided voters have an unfavorable impression of Romney, while his favorability ratings are mired in the teens. That’s an average net-favorable rating of -33, which is all the more remarkable considering that about one-third of voters didn’t offer an opinion of Romney at all. Put differently, Romney is disliked by an astonishing 75 percent of undecided voters who have formulated an opinion of the Republican nominee…

Between some portion of undecided voters staying home, an inevitable subset voting for Obama, and Romney’s high unfavorable ratings, a flood of undecided voters flocking to Romney seems unlikely—at least if the election were held today.