In the now-cast, Romney crosses 20% with downward momentum. It is really, really hard to win the electoral college without winning Ohio, and really hard to win Ohio if the polls six days before put you down by 3%.
As Nate writes:
Mr. Obama is not a sure thing, by any means. It is a close race. His chances of holding onto his Electoral College lead and converting it into another term are equivalent to the chances of an N.F.L. team winning when it leads by a field goal with three minutes left to play in the fourth quarter. There are plenty of things that could go wrong, and sometimes they will.
But it turns out that an N.F.L. team that leads by a field goal with three minutes left to go winds up winning the game 79 percent of the time. Those were Mr. Obama’s chances in the FiveThirtyEight forecast as of Wednesday: 79 percent.
Not coincidentally, these are also about Mr. Obama’s chances of winning Ohio, according to the forecast.
we’re at the point now where Mr. Obama may be a modest favorite even if the national polls are right. Two weeks ago, when Mr. Obama appeared to trail Mr. Romney by a point or so in the national polls, that would not have been the case...