If you go onto the RealClearPolitics map and tool around, you can see how tough this will be for Mitt. Pick just two large battleground states as "gone" and the odds become nearly insurmountable.
For example, let's take VA and FL off the table.
NC should be relatively safe... McCain only lost by 14000 votes... so allright, assume that's in his column.
Then give Romney IA, MI, OH, and WI. (His campaign has been clear in trying an upper midwest strategy). Each of these is tough to do, but there is a plausible argument in each, that a win is possible.
Let's assume liberty folks are totally over-rating their influence, and Romney wins NH and ME despite the convention animosity.
Obama still has a 274 to 264 lead. Where do the other electoral votes come from?
PA, NV, and CO would be the only plausible states left. None of those look like good bets though. Even if he can win one of them it's worth re-assessing my earlier assumptions. Can he really win *ALL* of the upper midwest? I doubt it, something will not "break" his way among them. Is Maine really going to vote for him? Seriously?
Furthermore, no matter what, Obama will probably get an electoral vote in Nebraska (where Lincoln is) and one of them in southern Maine. 2 more votes to make up, that could become critical in the end for Romney.