The idea that Democrats have some demographic destiny to become the majority party no matter what they do or don’t do is frequently criticized on both factual and moral grounds, and quite rightly so. But there’s obviously some truth to the premise that all other things being equal (which they rarely are), Republican insistence on being the White Man’s Party along with the presidency of Barack Obama gives Democrats an advantage among nonwhite voters that’s hard to lose. And it certainly matters in places where the number of nonwhite voters is rising significantly.

One such place is Georgia, and today Nate Cohn of The Upshot suggests that underestimation of demographic change in that state could be affecting polls showing Democrat Michelle Nunn narrowly trailing Republican David Perdue in a key Senate race.

For all the hype about “Purple Texas,” the real front in the Democratic demographic offensive is Georgia.

No other plausibly competitive state has seen a more favorable shift for Democrats in the racial composition of eligible voters over the last decade. The pace of demographic change is so fast that Michelle Nunn, a Democrat, is locked in a tight race against the Republican David Perdue for an open Senate seat — even with an off-year electorate that is favorable for the G.O.P.

The pace of demographic change might even be fast enough to outpace the polls.

Turns out some polls may be using outdated census data to “weight” poll results in terms of the expected composition of the Georgia electorate, which could be significant since the white share of the adult population in the state has been dropping by a remarkable one-half-of-one-percent each year over the last five years. And there are other issues:

Another possibility is that the likely-voter screens — in which pollsters estimate who will vote and who won’t — are excluding too many black registered voters, either because the screens are too tight or because Democratic mobilization efforts aren’t yet underway.

One pollster has raised this possibility. Mark Schulman, chief research officer at Abt SRBI, noted that The Atlanta Journal-Constitution/SRBI poll applied a “fairly tight” likely-voter screen (eliminating people who said they were less engaged in the election, for example). Black voters represented 24 percent of the electorate in the poll, compared with 28 percent in 2010. Mr. Perdue led by four points; it would have been a dead heat if the black share of the electorate were four points higher.

Of course, the black share of the electorate might not stay as high in 2014 as the 28.2 percent share in 2010. Black turnout, for instance, might well go up, but white turnout might go up even more. But we can safely dismiss the possibility that the black share of the electorate will crash into the mid-20s — and that’s where several of the most recent polls put it.

As Cohn notes, even if polls are underestimating the nonwhite and hence the Democratic vote in Georgia, it will still be difficult for Michelle Nunn and Jason Carter to top the 50% necessary to avoid a general election runoff, in which (traditionally) the white share of the vote is usually quite a bit higher. But I’ll say this: if the 2016 presidential election is competitive, Georgia, which now has 16 electoral votes, is going to be seriously in play for the first time since 1992.

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Ed Kilgore is a political columnist for New York and managing editor at the Democratic Strategist website. He was a contributing writer at the Washington Monthly from January 2012 until November 2015, and was the principal contributor to the Political Animal blog.