So, the long story short is if Obama loses, its because Democrats can't run campaigns.
Two words: early voting.
Obama and the Democrats are going to spend a ton more money trying to drive up turnout with early voting by mail, just like they did in 2008. Making it easier to vote is the ultimate cure for apathy and it prevents anybody from changing their minds late.
The fact that nobody is talking about it makes it our October surprise: results will be closer to the registered model than likely on the backs of early voting. Obama's winning this thing, folks.