Below is a 272-266 Obama win.
Every state that voted for Obama in '08 by less than his national margin is given to Republicans, and vice-versa.
If Republicans are going to win, they're probably going to win back all the states I've given them here, and they need to win only 1 more. Which would it be, assuming Romney is the candidate?
With a stagnant or declining economy the map is far more likely to resemble something like this rather than that:
In other words, the question is not how Romney is going to win a close election, but how many states is Obama going to lose if the economy does not unexpectedly bounce back next year? If we have a double-dip recession, especially if it is announced in late summer, the only electoral votes Obama is definitely assured would be Hawaii and DC. It could get THAT bad...