Real Clear Politics LINK has a series of state by state tracking polls for the 2012 presidential election. This type of analysis, used to perfection by Nate Silver of 538.com fame turns out to be the best predictor of final results on election day (Silver was 100% correct in 2012 using this method).
Here is the final Electoral College map for the 2012 election
with 270 needed for victory;
If Florida/Virginia/Colorado, all states that Romney led in in October, which totalled Electoral 51 college votes, were added to the 206 he received on election day, he would have ended up with 257 Electoral College votes 13 short.
Thus even with the best case scenario and if he had remained gaffe free Romney still needed Ohio. Romney and his team thought, through their internal polling that they had that state won. But applying the Nate Silver rule, and looking at the tracking polling, it is clear that at no point at all did he have a lead in Ohio, even after Romney's lift in the polls after his first debate with President Obama. For the record Neither did Romney lead at any point in Iowa.
Could the Republicans have won in 2012? Given the history of the difficulty of dislodging a sitting president and with some ambivalence regarding ascribing all blame for the stagnant economy to President Obama it would seem unlikely.
It does seem likely though that a more conservative candidate, one who didn't have Romney's baggage of Romneycare, his elitist language and image and his Mormonism
might have persuaded the millions of Perot-ite voters who stayed home to vote. That may have been just enough to swing Ohio and perhaps the election.