Obama has the late-campaign metrics on his side, according to Charlie Cook at the National Journal:
The metrics of this election argue strongly that this campaign is over, it’s only the memory of many an election that seemed over but wasn’t that is keeping us from closing the book mentally on this one. First, no candidate behind this far in the national polls, this late in the campaign has come back to win. Sure, we have seen come-from-behind victories, but they didn’t come back this far this late.
Read the article for the persuasive reasons why.