In early May, researchers from Monmouth University asked respondents to a national poll whether they planned to vote by mail in the November presidential election. The question had new salience with the emergence of the novel coronavirus, a development that introduced new risk to the traditional in-person voting process. At the time, about half of Americans said that they intended to do so, a substantial increase from the 36 percent of ballots cast early in 2016.

On Tuesday, Monmouth released a new poll that asked the same question — and it yielded the same overall response. As was the case three months ago, about half of Americans said they intended to vote by mail. But that similarity to May hides the real shift under the hood.

In May, Democrats were about 30 percentage points more likely to say they were very or somewhat likely to vote by mail than were Republicans. And about 4 in 10 Democrats insisted that they were very likely to do so, compared with about half as many Republicans.

Since then, both parties have shifted dramatically, in opposite directions. Democrats are now 50 points more likely to say they’re at least somewhat likely to vote by mail, with fully half saying they’re very likely to do so. Meanwhile, the number of Republicans saying they will probably vote by mail has fallen to 22 percent.

What changed? You know one key answer to this: the public position of the president of the United States.

Earlier this year, President Trump decided that he would publicly and vociferously oppose the idea of mail-in voting for the November election. He came out in public opposition to mail-in voting when it was proposed for the Wisconsin primary in early April in an effort to reduce transmission of the coronavirus — after seeing a segment on “Fox & Friends.”

“Republicans should fight very hard when it comes to state wide mail-in voting,” he tweeted then. “Democrats are clamoring for it. Tremendous potential for voter fraud, and for whatever reason, doesn’t work out well for Republicans.”

The election Trump was most concerned about in Wisconsin, a state Supreme Court race, in fact did not work out well for Republicans — but that was more because of Trump’s energetic focus on the race and the still-going Democratic presidential primary than because of absentee voting.

By May, he had decided to take a fervent, vocal stand against the practice. His complaints were resuscitated during a special election in Southern California early in the month (which Republicans won) and accelerated as the weeks passed. He made various false claims on Twitter about how mail-in ballots work, prompting the social media company to flag his tweets as misinformation — energizing Trump to embrace the issue even more vocally. That continues to this day, with Trump even beginning his coronavirus briefing Monday with an aside about the purported/exaggerated risks of mail-in voting.

The first Monmouth poll was conducted before the California special election, giving us a decent sense of how much the views of partisans have shifted relative to Trump’s embrace of the issue. While the new Monmouth poll can’t specifically attribute the shift among Republicans to an embrace of Trump or among Democrats to a rejection of him, it’s hard to believe that the changes are independent of Trump’s elevating the issue.

Part of Trump’s focus on the issue is probably rooted in his long-standing misrepresentation of the frequency of voter fraud in general. If he doesn’t believe that voter fraud is rampant, he’s shockingly good at acting as if he does. Certainly some part of his focus on the idea that fake votes are cast derives from his desire to believe that his popular-vote loss in 2016 wasn’t a loss at all or, at least, wasn’t as bad as reported. But he was alleging that fraud would occur well before Election Day that year, obviously as part of a similar effort to rationalize away a seemingly likely electoral loss.

Now, his motivations are murkier. Part of it again is certainly that he wants to be able to walk away from his reelection campaign claiming that he’s a winner, even if that claim depends on his assertions that millions of ballots cast for his opponent were somehow generated illegally. But it may also be an effort to stopgap such a loss, driving Republicans to in-person voting in hopes that he can point to the results on election night as definitive, casting more-heavily Democratic votes counted in the following days as suspect.

Would he do this? Of course he would do this. In 2012, he briefly called for a revolution under the mistaken belief that Mitt Romney had won the popular vote but lost the electoral college. (As more votes were counted, it became clear that Barack Obama won both.) In 2018, Trump advocated for upholding the results of close gubernatorial and Senate races in Florida as of election night, claiming falsely that subsequent ballot-counting that again favored the Democratic candidates should be considered suspicious.

Votes that come in after Election Day tend to skew Democratic for a few central reasons, as Cook Political Report’s Dave Wasserman pointed out on Tuesday. Big cities have more Democrats and more voters — so more votes to count after the fact. Provisional voters, who cast in-person ballots that need to be reviewed, tend to be members of Democrat-heavy demographic groups. Same-day registrants who can vote in some states tend to be younger and therefore more heavily Democratic.

This year, we have the added reason manifested by the Monmouth poll: More Democrats intend to use mail-in voting specifically because of the pandemic (and, it seems, to spite Trump). That doesn’t necessarily mean that their ballots will be counted late; in many places, ballots received before Election Day are counted in advance of polls closing. But it does increase the chance that, as ballots are counted after the election, the results will bend away from Republican candidates, including Trump.

This overlap between Democratic and early voters is an obvious reason that Trump and his allies are seeking to constrain mail-in voting. Just as there have been numerous efforts to constrain in-person voting in ways that disproportionately disenfranchise Democrats (such as voter-ID laws), there’s an effort this year to make it harder to cast ballots by mail. This has been frustrating to Republican activists in some states, such as Florida, where an April tweet from Trump disparaging mail-in voting was tweaked by his own party to make it more absentee-friendly. (Trump later explicitly endorsed mail-in voting in Florida, claiming falsely that somehow the state had eliminated whatever problems he alleges exist.)

The flip side to this, of course, is that voting in person may, in fact, be more dangerous for voters, including the two-thirds of Republicans who say it’s not at all likely that they’ll vote by mail. Republicans tend to be older, as well, a group that’s more at risk from the coronavirus.

A cynic might note that any surge in infections caused by voting in a confined polling place would become apparent only a few weeks after Election Day, probably well after the contest is determined. But not necessarily. We could certainly see a situation in which cases are surging as Trump is attempting to frame ballots that are trickling in as broadly suspect, clinging onto the White House for dear life.

Enjoy your summer. Things may be about to get even weirder.