President Trump's base has gotten smaller.
That's a key finding of an analysis of how the U.S. electorate has changed since 2016, based on census data analyzed by the Brookings Institution and NPR.
In 2016, Trump was helped to victory by winning a record margin among white voters without a college degree. But in the last four years, they have declined as a share of the voting-eligible population across the U.S. and in states critical to the presidential election. Nationally, the group has gone from 45% of eligible voters to 41%.
Meanwhile, some other demographic cohorts — whites with a college degree, Latinos and, to a lesser extent, Asian Americans and other groups — have all gone up.
The trend holds in the battleground states as well.
Of the 16 states most likely to be closely contested this election, all but two have seen a decline in whites without a college degree as a share of eligible voters. College-educated whites, on the other hand, have gained in 14 of those states, according to the analysis.
Latinos are on the rise in 12 of the 16 states, most notably in the Sun Belt, where Asian Americans are also a significant share.
With Trump facing an uphill reelection battle, the findings underscore that it's not just that he's winning smaller margins among some key groups, according to public opinion surveys, as compared with 2016 — but that the pool of people who appear most open to his message is shallower.
"Demography keeps moving along," said demographer William Frey, a senior fellow at Brookings who compiled and analyzed the data.
A shrinking gap
Almost two-thirds of whites without a college degree voted for Trump in 2016, and they are still among the largest voting blocs in the country. But the gap between them and other more Democratic-leaning groups is shrinking.
For example, when you combine whites with a college degree and Latinos, two groups that have voted far more in favor of Democrats, they are now almost on par with whites without a degree.
That's a big shift from 2016. Then, whites without a college degree had a 9-point advantage over whites with a degree and Latinos combined. Now, the gap is only about 2 points.
A decline of whites without a college degree in the Rust Belt
Trump was able to eke out an Electoral College victory in 2016 by fewer than 80,000 votes in three critical formerly Democratic states — Michigan, Wisconsin and Pennsylvania.
So given that he was operating at such a narrow margin already, Trump can't afford to lose voters there. But that may be what's happening in the Rust Belt.
There are seven battleground states where whites without a college degree are a majority of eligible voters. All of them, except New Hampshire, have areas included in the Rust Belt. And in each of them, whites without a degree have declined.
In some places, like Pennsylvania, New Hampshire and Ohio, they've gone down significantly, by 5 percentage points as a share of eligible voters.
Conversely, whites with a college degree have gone up in each of them. These states are less diverse than other places, so this educational split among whites is one of the most important factors in determining whether Trump or Joe Biden wins them.
Diversifying Sun Belt
The U.S. is diversifying more quickly in the South and West, and we've seen traditionally Republican Arizona, Georgia and Texas emerge as battlegrounds.
Demography is largely responsible for that. In four key Sun Belt states, including Florida, the share of non-college-educated whites has gone down, while Latinos are on the rise.
In Arizona, in particular, whites without a college degree are down 5 points since 2016, and Latinos are up 6. Latinos now make up almost a third of the voting-eligible population in the state. In 2016, they made up only 15% of voters, according to exit polls, so registering Latinos to vote is critical there for Democrats, something made more complicated by the coronavirus pandemic.
The fact is this: Latinos are simply aging into the voting-eligible population. In 2018, whites for the first time made up a minority of America's under-15 population.
So even if immigration were shut off completely today, Latinos would only continue to become a larger share of eligible voters over the next generation.
Yes, but who will turn out?
None of this is to say who will turn out to the polls. This analysis is looking only at people eligible to vote, not who will show up — and those are very different things.
That's why the campaigns are working so hard to turn out their voters, especially now with hyperpartisanship dominating. For Trump, that means getting out more white non-college-educated voters.
Trump may have won a record margin among whites without a college degree, but their turnout rate was not remarkable as compared with past presidential elections. In fact, it was lower than in both 2008 and 2004.
Trump has done very little to reach out beyond his base. But as the Cook Political Report's David Wasserman has noted, half of all nonvoters in 2016 were whites without a college degree.
So, on the one hand, there's clearly room to grow for Trump with his base group of voters.
On the other hand, it's unclear why they would turn out for Trump at higher levels than in 2016. Majorities of Americans this year disapprove of the job he's doing overall and his handling of the coronavirus pandemic.
What's more, Hillary Clinton isn't on the ballot. Biden is seen far less negatively than Clinton was.
Still, the need for white non-college-educated voters to turn out in larger numbers for this president might well explain the culture-war messaging and crime warnings of the now-wrapped-up Republican National Convention.