Americans’ use of mail-in ballots has skyrocketed since the pandemic — and President Trump’s criticisms of mail-in voting have increased, as well. “I think mail-in voting is going to rig the election, I really do,” Trump said in a July interview with Fox’s Chris Wallace. As more states moved to expand voting by mail to help protect citizens from the coronavirus, Trump’s criticisms intensified in tweet after tweet, calling mail-in ballots “substantially fraudulent” and open to cheating. In last week’s presidential candidate debate, Trump was at it again, lambasting what he called “unsolicited” mail-in ballots.

Have Trump’s attacks changed the way voters remember their own voting history? Yes, we found in our recent research. Trump supporters who have usually voted by mail in the past are more likely to say they have not, aligning themselves with the president.

How we did our research

Our University of Florida-based team conducted an email survey of Florida registered voters between July 21 and Aug. 1. We got their email addresses from a publicly available statewide Florida voter file available from the Florida Division of Elections. Our survey hit the field just two days after Trump was interviewed by Chris Wallace on “Fox News Sunday,” during which he once again railed against mail-in voting.

In our survey, we included a variety of questions aimed at discerning the respondent’s level of concern over contracting covid-19; which presidential candidate they intended to vote for in this election, and what vote method they usually use to cast ballots. We then linked our respondents to the statewide voter file and vote history file to find obtain their validated method of voting in the 2016 and 2018 general elections.

More than 11,000 people responded to our survey, a group demographically very similar to the entire population of Florida voters. Of those, we could see in the validated public voting record that about 4,000 (including 1,552 Republicans) respondents had voted by mail in both the 2016 and 2018 general elections.

Of those who recently voted by mail, Republicans were most likely to deny having done so.

Among other things, we asked survey respondents to report what voting method have they used in the past. We then checked their answers against their validated voting records to see if they reported accurately. Of those who had in fact voted by mail in both 2016 and 2018, roughly one in four Republicans — and nearly one in three Republicans who identified themselves as Trump supporters — incorrectly reported they did not usually vote by mail. In contrast, only 10 percent of Democrats and 15 percent of independents in this group misreported, saying instead they usually vote in person.

Why might this be? It’s possible that these respondents considered the last two general elections aberrations from their normal practice over their lifetimes, and therefore answered “usually” from that lifetime view. But if so, why might Republicans be more likely to do so than others?

Social science tells us that partisanship can shape beliefs and actions. Especially in a country as polarized as the United States is now, those who identify strongly with their party tend to internalize party leaders’ cues and alter their beliefs and behaviors to conform. Like most people, Republicans and Democrats tend to seek out and retain information that confirms their partisan biases, and to reject information that does not fit their belief systems. Social scientists call that subconscious process “motivated reasoning.”

Trump’s criticisms of mail-in voting has sent Florida voters clear cues on what to think about mail-in voting. A significant portion of Republicans are willing to renounce their recent voting method to follow their party’s leader.

However, we also asked respondents whether they were concerned about getting sick from the coronavirus. Among Republicans who voted by mail in the past two general elections, those who answered that they did fear contracting covid-19 were much less likely to misreport how they normally vote, as you can see in the figure below.

What does this mean for the 2020 election?

Trump’s claims against voting by mail can hurt citizens’ trust in the electoral system, increasing partisan politicization. We can see that in our survey, which finds a sizable number of Republicans — Republicans who habitually mail in their ballots — are willing to renounce that habit and follow their leader, especially if they’re Trump supporters. That’s mitigated somewhat if they’re concerned about the pandemic.

Enrijeta Shino is a political scientist at the University of North Florida. Daniel A. Smith is a political scientist at the University of Florida