Kind of a sad indictment of Romney's campaign message that it boils down to a single very vague, undetailed message, while Obama's campaign has so much effective material to pull from they can basically run a dozen micro-campaigns. Romney just doesn't have one message, he basically has no message. Just lots of cash.
Romney is a fundamentally bland, unappealing candidate. He can't win if it's Romney vs. Obama. He basically has to make the election Obama vs. Not-Obama.
While it's true there are paths to victory without OH, Romney certainly can't concede it, and the money spent there will hurt him in other areas. Can you imagine the headline "Romney pulls out of Ohio"? Disastrous.
He can't pull out of Ohio because he has no other viable route to victory. I realize it may be technically possible for him to get to 269 EV without winning Ohio, but the real problem is that if he can't win Ohio, it's unlikely he'll be able to win Wisconsin, Iowa, Colorado, or Virginia, and he needs to win at least two of them if he loses Ohio.
