In the continuing effort by pollsters to figure out why their numbers didn’t hold up on election day, a new survey by the Institute for the Study of Citizens and Politics indicates that the polling numbers weren’t that far removed from reality. Indeed, the disparity seems to be that an unusual number of Americans broke for Donald Trump in the final two weeks of the campaign.

The survey is part of a FiveThirtyEight project that polled a panel of the same voters throughout the election. With this method, they were able to get a clearer sense of how specific voters were responding to the roller coaster election process. According to Nate Silver, the last pre-election panel survey had Clinton in the lead by a healthy margin.

“Our October 2016 wave was conducted with nationally sampled adults over age 26 between Oct. 14 and Oct. 24, meaning that it ended soon after the third Clinton-Trump debate,” Silver wrote. “At the time, Clinton was riding high in the polls — and 43 percent of our panelists in that wave expressed support for Clinton, as opposed to 36 percent for Trump.”

But those numbers have shifted, if only slightly. According to the panel’s post-election survey, 89% of the respondents stuck by their October preferences. But a small fraction – 0.9% – moved from Hillary Clinton to Trump. As Silver put it, that number may seem insignificant, but “if there were a comparable swing in the national electorate, 1.2 million votes would move to Trump.”

Adding to Trump’s fortunes, 3.1% of undecideds in the October survey chose Trump in the post-election poll. Clinton picked up only 2.3%.

In a tight race that ultimately came down to less than 100,000 votes in a few key states, that kind of swing could explain why Trump – widely expected to lose going into election day – pulled off the big upset on November 8th.

This revelation will add fuel to the claims that FBI Director James Comey, by briefly re-opening the investigation into Clinton’s email debacle, wound up handing the presidency to Trump.

Is that fair? Perhaps. It might have made a difference. After all, you can’t blame voters for being disgusted with the whole thing. Beyond the emails, we’ve got Hillary’s closest advisor’s husband sexting with teenage girls – not exactly the kind of people you want surrounding the next president.

The much likelier explanation, though, lies with Trump’s post “Access Hollywood” campaign. The Republican nominee was extremely disciplined in the closing weeks, and his Teleprompter-focused speeches may have been enough to convince wary conservatives to come home to the GOP.

Whatever the cause, it just goes to prove the old saying: The only poll that counts is the one taken on election day.