He doesn't have a choice.
If Romney loses Ohio, he has to take NH, Iowa and Nevada to make up for it. It can be done, but it seems unlikely. Hell, even if he takes Ohio he needs to hold Colorado and Florida while winning Virginia.
The electoral college remains a nightmare. Without Ohio in his pocket, it's less of a nightmare and more of a deathblow.
"Tact is the ability to tell someone to go to hell in such a way that they look forward to the trip"