Ambers has a good post on the "known unknowns" that remain central to the election. Some, like latent racism, benefit McCain. But a fair number benefit Obama. You're not hearing as much about them because it's not very interesting to say that his GOTV machine could render his vote share two percent larger than it would otherwise be, or dispirited Republicans might stay home and turn a solid win into an utter rout, but they exist. On a predictive level, my sense is that Obama's popular vote margin is going to be quite a bit higher than his electoral vote tally. There's a certain set of left-leaning voters in places like California who don't turn out because their vote doesn't matter. But anecdotally, I'm hearing a lot of folks this year who want to vote for Obama not just because they want to assure his win, but because they want to be able to say they voted for the first black president. They want to be part of this moment, if it indeed manifests. So the rational decision to forgo the inconvenience of voting is overwhelmed by the desire to have been a participant. If that effect is as big as I think it might be, it could pump up Obama's popular vote totals rather significantly. Update: Julian Sanchez e-mails to note that it makes no sense to say "Obama's popular vote margin is going to be quite a bit higher than his electoral vote tally." I certainly don't think Obama will break 60 percent in the popular vote, though he could well do it in the electoral vote. What I meant is that I think his electoral vote tally might come in lower than expected -- I think there's a fair chance he loses Ohio -- while his popular vote significantly outperforms his polling.
