Don Surber recounts the 2008 electoral college using Obama's current state-by-state approval numbers...

... and figures Obama would lose if the election were held today.

But approval numbers don't answer the question whether Obama would win when pitted against a particular candidate. Even if a poll asked people whether they'd vote for Obama over an unnamed Republican candidate, those imaginary opponents tend to do better than real candidates. You've got to account for all the voters who disapprove of both candidates but still have to vote for someone.