At the end of the day enough independent voters and Democrats found Romney appealing, just as independent voters and many Democrats always found Ronald Reagan appealing in his governor’s races in California. Reagan usually ran ahead of his polls, too. Both Reagan and Romney are what common sense observers might call “voting booth” candidates—people that you end up being comfortable voting for when you walk into the booth still slightly doubtful about the choices. I expect that Romney will win any state where good polls show him running even with Obama over the last weekend.
When journalists and historians look back over this campaign, they will surely point to the first debate on October 3 as the turning point, which is correct, though it is going to upend all the conventional wisdom of academic political science that debates don’t matter much or affect the results much. I’m sure there will be lots of fancy and mostly unreadable journal articles “proving” Romney’s debate didn’t really make any difference. But that’s why no one pays much attention to academic political scientists.