In fact, about “13 percent of the electorate says it’s undecided or will vote for a third-party candidate, as compared with just 3 percent in the final 2012 polling average,” as Nate Silver at FiveThirtyEight explains.

Silver cites those figures in the context of a broader discussion of this election’s uncertainty: At this point in 2012, his “polls-plus” forecast gave Mitt Romney just a 9 percent chance of victory over Barack Obama. Right now, that same model gives Donald Trump a 35 percent shot at beating Hillary Clinton. Indeed, the race has so tightened that by Silver’s calculations, “Clinton has 268 electoral votes in states where she’s clearly ahead in the polls — two short of the 270 she needs.”