President Trump famously declared during his 2016 campaign that he loved the “poorly educated” because voters with lower levels of schooling delivered an overwhelming share of votes to him.
Four years later, political pros say most of those folks remain enchanted by the president, but it’s anyone’s guess whether they turn out to vote in the same numbers and whether they will remain attached to the Republican Party after Mr. Trump leaves the presidential stage.
Why Mr. Trump appeals to them is also heatedly debated. Explanations include economics, race and the president’s blunt style of rhetoric.
What is not in dispute, though, is how deeply Mr. Trump resonated, particularly among White voters without four-year college degrees, and how much it upended the political playing field.
Patrick Murray, director of the Monmouth University Polling Institute, said there wasn’t much of an education gap among White voters before 2012. Those with college degrees were about as likely to vote Republican as those without.
That began to change in the race between President Obama and Republican opponent Mitt Romney, but it exploded in 2016 when Mr. Trump got the support of 51% of voters without a college degree. Among White voters without a college degree, he bested Hillary Clinton by 35 percentage points, Mr. Murray said. Among white voters with a college degree, the two ran even.
That has changed somewhat.
Mr. Trump’s lead over Democratic nominee Joseph R. Biden among White voters without a degree is 25 points in Monmouth polling, Mr. Murray said. But Mr. Biden holds a 15-point lead among White college-educated voters.
“But the unprecedented yawning gap between those two groups remains,” he said.
Mr. Trump’s surprise 2016 victory sent political scientists scrambling to figure out what happened. Early speculation revolved around a pool of voters who backed Mr. Obama and then switched to Mr. Trump.
Michael Sances, an assistant professor at Temple University, crunched the numbers and said the level of party-switching wasn’t high compared with previous elections, but those who did switch in 2016 were heavily concentrated among lower-educated voters.
“There aren’t many, but in a close race, they can be key,” Mr. Sances said.
He looked at counties and compared their votes from 2012 and 2016. If the counties at the bottom 20% of education attainment had voted for the same party in both elections, then Hillary Clinton would have won the Electoral College by about 30 votes.
Mr. Trump’s appeal to less-schooled voters became apparent early in the 2016 Republican primary season. After several stories pointed out his success with that demographic, Mr. Trump declared, “I love the poorly educated.”
That phrase went viral, and some less-educated voters took to Twitter to insist they didn’t like Mr. Trump.
Others, presumably in the more-schooled crowd, complained that it was a bad look for Mr. Trump to brag about winning the demographic.
Mr. Trump was lucky, though, that the vote of a high school dropout counts as much as that of someone with a Ph.D. or law degree, but those who hold degrees are increasingly crowding out the less-educated.
As recently as 2004, those without four-year college degrees made up 58% of the presidential year electorate. That share has fallen in each election since and reached just 50% in 2016.
Broken down further, 18% of voters in 2016 never went beyond high school, 32% had some college but didn’t graduate, 32% did graduate and stopped there, and 18% had postgraduate schooling.
Some academics have suggested that the divide is not about education. Trump voters in 2016 just weren’t as intelligent, said Yoav Ganzach, a professor at Tel Aviv University.
He led a research paper that used data from the American National Election Studies to judge voters’ verbal abilities, as a proxy for intelligence, and then compared those abilities with their choices in the 2016 election. The paper argued that “support for Trump was less about socioeconomic standing and more about intellect.”
Gordon Pennycook, a cognitive psychologist and assistant professor at the University of Regina in Canada, used cognitive reflection test scores of more than 15,000 people who participated in studies on Mechanical Turk, a research tool, to judge their approaches to voting in 2016.
He found that Trump voters, particularly Democrats, were “less reflective” than Clinton voters.
He said there is no strong evidence for the attraction, but it could be that Mr. Trump speaks in a simple and repetitive way.
“That might be something that draws people who tend to have a more intuitive mindset in the first place,” the professor said.
Republicans and conservatives who voted for the Libertarian candidate or other third-party nominee rated highest on the cognitive reflection test, and those who did not vote at all showed the lowest scores overall.
Whether those voters stay with Republicans for the long haul is tricky to predict.
Mr. Pennycook said “the nature of being highly intuitive means you don’t think your way out of where you were,” but going with a gut feeling can make a voter more easily moved by the surroundings.
“It’s hard to predict what’s going to happen,” he said. “It’s pretty close to random, basically.”
Michael McKenna, a former Trump White House aide who now writes a column for The Washington Times, said Mr. Trump’s attraction for working-class voters — those likely to lack college degrees — should be obvious. He is talking about the pain of globalization and competition from China, to communities that have suffered deeply.
“Trump’s the first guy — love him, hate him, be indifferent to him — he’s the first guy that’s said, ‘You know, I don’t think this is right. I don’t think this is healthy for the country long-term,’” Mr. McKenna said.
The other side of that coin are suburban voters who benefit from globalization and the cheaper prices they pay for goods at Target.
Mr. McKenna said the Trump effect will be lasting, though not necessarily tied to Republicans. Both parties can make a play for those voters.
“Trump has now opened this door,” he said. “In every election here on out, we’re going to have a candidate who will speak to the negative effects of globalization.”