I fully agree with Dave Weigel's takedown of William Galston's latest effort to argue Ohio Uber Alles -- that Barack Obama must win Ohio in order to win reelection.
I'd just add: this is really the wrong way of looking at elections from two years, eighteen months, even six months out. There aren't magic "Ohio" things that a president, over the long run, needs to do separate from the things he should do to keep his overall approval rating up. Neither are there magic "white working class" things he should do. If the economy thrives, Obama is going to do better everywhere, and among all groups. Sure, it's not necessarily the case that gains and losses are going to be exactly equal across the board...but it's also not the case that presidents can really calibrate what they do to affect that, very much.
Of course, it's sometimes the case that a president can direct resources to one state, or one region, over another, but most of those choices are relatively small, and matter either over the very long run or, more likely, only matter around the margins. That is, only matter to the economy around the margins. As far as the rhetoric of cultural inclusion that Galston is selling...well, I'd need to see some evidence that changed rhetoric about such things by an incumbent president could possibly have any significant effect.
Now, Ohio is certainly a close & big state, and therefore important in presidential elections -- although, as Galston's numbers show, it leans slightly to the GOP. The odds are that Ohio will go to the winner; that, of course, is true for all the close states (that is, in a blowout election, the "close" states won't actually be close; they'll be blowouts, and the states that wind up close will be the ones that tilt solidly towards the party that's losing: see Indiana, 2008). But since Ohio does tilt however slightly to the Republicans, it is possible for Democrats to win without it. More to the point, however, the best things that Obama could do to help himself in Ohio right now are generally the same things that would help him in Colorado, Florida, Virginia, Nevada, and everywhere else.