Why has style trumped substance, truth, consistency?
Rationally it doesn't make sense until you factor in that Obama isn't widely liked. I think for some, it is the color of his skin and I suspect this is a reason for the rise of the Tea Party. For others, it is what is perceived as intellectual elitism.
I think once Romney was seen as a regular guy and not some conservative radical a lot of people felt more comfortable supporting him.
If this is true, and Obama doesn't have a firm hold on 50.1% of the vote, then he doesn't have to just outperform Romney he has to hope for a Romney implosion.