We also have to keep history in mind. Over the last quarter century, party identification on Election Day has actually been quite stable in presidential elections.
Also, Compare Obamas average lead or deficit to the average Democratic identification edge (among the voters), and you can get a solid gauge of the state of the race. For instance, consider these polls currently included in the RealClearPolitics average. All of them provide the head-to-head numbers between Obama and Romney as well as the partisan identification of those included in the poll.
Right now, the average across the polls is about a one-point lead for Obama; there's also a Democratic registration advantage that fits in with the long-term trend. That suggests right now, this is a pretty solid take on the state of the race.