With national polling as tight as it is in this race, the historical observation that no Republican has entered the White House without the blessing of Ohio voters becomes a sort of predictive truism —the all-important brick in an impregnable swing state "firewall" that the Obama campaign would like us to put our faith in.
But, national polling is little more than a cheerleading exercise given the tough electoral math facing Mitt Romney from the beginning. To win, Romney had to do just three things: 1) Win Florida, 2) Win back the eastern states Obama took in 2008; North Carolina, Virginia, Indiana, and Ohio, and 3) Win one more state.
Despite the GOP's improved ground game in Ohio (and everywhere, compared with 2008) a Romney win looks unlikely — he hasn't ever been ahead in the Real Clear Politics polling average.
Karl Rove has said there are "11" ways to win without Ohio, but it doesn't seem like there are quite that many. National Journal's Josh Krashauer tweeted that Romney must, after winning the south and Colorado, "[pick] off Iowa and one other Rust Belt state." He's right that Obama has struggled with white working-class voters nearly across the board, but that's unlikely to be enough to put Pennsylvania in play. So Romney's path is actually narrower than that — he would have to win Colorado, Wisconsin, and either Iowa or New Hampshire to get to 270.
The GOP nominee has a slight lead among early voters in Colorado and polling there is roughly even. Contra Krashauer, the key factor in the race won't be undecided white working-class voters breaking hard either way; it's about how many supporters each campaign will be able to get to the polls. Because of their substantial organizing infrastructure in Wisconsin, the GOP's showing could be a lot stronger than any of the polls are predicting (remember how the Scott Walker recall election was supposed to be close?).
In Iowa and New Hampshire both, the race is extremely tight. The Public Policy Poll in Iowa is telling; through most of the year Obama was up by 5-7 points, but in their latest Romney was up by one.
So Romney could pull it off, and Ben Domenech predicts he will, but it's an uphill battle.