In George Packer's New Yorker piece about the working-class voters of Ohio, he quotes two old ladies in a diner:
"I don't know anyone who's for Obama," said Jennice, a Democrat who supported Hillary Clinton and who won't vote in November.
"If they are, they don't say it, because it would be unpopular," an elderly former teacher named Marcella said. That had not been true of Bill Clinton, Al Gore, or John Kerry, she added.
Now maybe there is a difference between what you'd tell a pollster and what you'd tell a reporter, but this exchange suggests to me that the so-called Bradley Effect, in which voters say they're for the black guy for appearances' sake but actually vote for the white guy, might be less likely than its opposite.
I bet there are quite a few of Jennice's friends who will end up voting for Obama in the privacy of their booth. The Ohio polls (which anyway have him ahead) may actually be underestimating his support.