There are certainly some good reasons to think that the polls could break toward Mitt Romney. For instance, many polls out now were conducted among registered voters; when pollsters switch over to likely voter polls instead — which assess each voter’s probability of actually casting a ballot on Nov. 6 — it is likely that Mr. Romney will gain a point or two. And Barack Obama obviously has a lot of weight to bear from the lukewarm economic recovery.
But one hypothesis you should find less persuasive is the notion that the polls will break toward Mr. Romney just because he is the challenger. [cont.]
Nate Silver, New York Times