Nate Silver says that Joe Biden’s mission tonight is to be the anti-Larry David — he needs to whip up enthusiasm.
From “Biden’s Debate Mission: Whip Up Democrats to Blunt Romney’s Gains,” FiveThirtyEight, NYT:
“When [Biden] takes the debate stage…, he will probably not be able to erase all of Mitt Romney’s gains in the polls after his debate performance….
“For the first time since Aug. 28, the FiveThirtyEight model projects Mr. Obama to win fewer than 300 electoral votes. But Mr. Biden may be able to do something about the yawning gap in enthusiasm between Democratic and Republican voters. That gap might be the greatest threat to Mr. Obama’s winning another term…, and it seems to have widened since the Denver debate.
“This year, the [enthusiasm] gap has been wider than usual. … But since the Denver debate, some polling firms have shown an especially large split between registered and likely voters.
“Gallup…found the split to be five points in Mr. Romney’s favor. That was enough to put him ahead by two points among likely voters in the Tuesday poll — even though he trailed Mr. Obama by three points among registered voters.
“Pew Research…found a four-point difference in their post-debate poll — enough to account for all of the lead they found for Mr. Romney.
“It is probably too late for Mr. Biden and Mr. Obama to do anything about the high level of Republican enthusiasm.
“In general, it is easier to persuade voters to turn out than to compel them to change their minds.
“It seems plausible that roughly half of Mr. Romney’s post-debate bounce…has resulted from the shift in enthusiasm. It will be Mr. Biden’s job in Danville to work on that half of the problem. Then Mr. Obama will need to improve his performance in the last two debates to get back the rest of what he lost in Denver.” Emphasis added.