Ruy Teixeira, the veteran Democratic election analyst who co-wrote the study with CAP senior fellow John Halpin, cautions that relying on demographic change alone to recapture the three blue-wall states would leave Democrats with virtually no room for mistakes if Trump improved on his 2016 performance there. But, Teixeira notes, the continually changing electorate means that Trump, both nationally and in battleground states, will likely need to squeeze more advantage from working-class whites—through either higher turnout or a bigger margin of victory—just to offset his weakness with the groups that are growing.

Read: Why Trump’s favorite 2016 map should scare him

If Democrats “are relying on demographic change to win, you are praying nothing else will change, and you are hoping to squeak out a victory by the tiniest margins,” Teixeira says. But it is a “bonus” for Democrats, he explains: “Even if [Trump] accomplished exactly what he did in 2016, he would probably lose the election. So he not only has to do that; he has to try to do more.”

Much remains unknown about the 2020 election, of course, including which Democrat will win the nomination, whether Trump will survive impeachment, and how it will affect his political standing if he does. But the study addresses one of the crucial baseline questions that will shape the coming election regardless of those other dynamics: How will the universe of Americans eligible to vote in 2020 differ from 2016?

To answer that question, the authors rely on demographic projections for the eligible voting population from the nonpartisan States of Change project, a joint effort by CAP, the Brookings Institution, the Bipartisan Policy Center, and the Democracy Fund Voter Study Group.

The composition of the population eligible to vote differs from the composition of those who actually vote, for two reasons: Eligible whites, especially those with college degrees, turn out at a higher rate than eligible minorities, and older people vote at a much higher rate than the young. That means eligible minorities and non-college-educated whites usually comprise a smaller share of actual voters, while college-educated whites, whose turnout levels exceed the other two groups, consistently represent many more actual than eligible voters.

But the eligible and actual measures have moved in tandem over recent decades, with non-college-educated whites consistently decreasing as a share of both groups, and both minorities and college-educated whites increasing. Even Trump’s strong appeal to working-class whites in 2016 only slightly altered these long-term trends. The new report concludes that those patterns will largely continue through 2020, complicating the electoral puzzle facing Trump, but also leaving Democrats on a slim ledge.

The study forecasts that whites without a college degree will decline as a share of eligible voters in 2020 by 2.3 percentage points. It anticipates increases for Latinos (1.3 percentage points), Asians and other minorities (0.6 percentage points), and African Americans and college-educated whites (both at 0.2 percentage points). That could translate into an actual electorate in which college-educated whites hold steady at about 30 percent of voters, non-college-educated whites slip to about 42 percent (from 44 percent in 2016), and minorities rise to make up the difference.