WASHINGTON — Those most likely to vote by mail in 2020 included some demographic groups that voted heavily for Donald Trump, new Census data show, undermining his claim that voting by mail only helps Democrats.

Older and more affluent voters were especially likely to vote by mail in 2020. Almost 54 percent of voters age 65 and older — who supported Trump by 5 percentage points, according to exit polls — cast votes by mail. Less than 40 percent of voters under 65 did so.

And 44 percent of voters making more than $100,000 a year voted by mail, compared to 40 percent for those making less. Trump won those more affluent voters by 12 points, according to exit polls.

As the coronavirus pandemic closed polling places and many states relaxed mail-in voting requirements last year, Trump claimed on Fox News that mail-in voting would ensure “you’d never have a Republican elected in this country again.”

The U.S. Census Bureau data were released as Republican state lawmakers around the country are proposing bills to restrict vote-by-mail, while their Democratic counterparts propose expanding it. The House passed legislation in March that would require states to make vote-by-mail available to all voters, but it remains stalled in the Senate because of Republican opposition.

But many down-ballot Republicans fared well under mail-in voting, and the new survey data confirm that some Republican-leaning groups were more likely to take advantage of casting their ballots by mail.

Mail-in voting seemed to have a remarkable effect on older voters with health issues. In 2016, 34 percent of seniors who didn’t vote said health problems or a disability prevented them from getting to the polls. In 2020, that number was less than 4 percent.

Other demographic groups also had smaller differences. White voters were more likely to vote by mail than Black voters, 43 percent to 35 percent. But Latino and Asian-American voters had even higher rates of mail-in voting.

Women were slightly more likely to vote by mail than men, and college-educated voters were more likely to vote that way than high school graduates. Although the differences were relatively small, those groups tended to vote more Democratic.

The Census Bureau has asked about voting behavior after every federal election since 1964, providing a comprehensive snapshot of who votes, how they vote — and why some people don’t vote. Last year’s survey included 54,000 households with citizens 18 years or older from Nov. 15-24, 2020.

Opinions on voting by mail have become politically polarized since Trump began attacking it last year. More states moved to expand the practice after the coronavirus pandemic hit and people were leery of going to crowded polling places.

Across the country, Republican state lawmakers are looking to restrict vote-by-mail, echoing Trump’s baseless claims that it leads to more ballot fraud and saying the moves would restore public confidence in elections. According to the Brennan Center for Justice, 190 bills restricting vote-by-mail have been filed in 46 states.

Recent laws in Georgia and Iowa cut the amount of time voters have to apply for mail-in ballots, restrict drop boxes and bar local elections officials from sending out mail-in ballot applications without a request, something many elections clerks did during the coronavirus pandemic.

Democratic lawmakers, meantime, are looking to expand vote by mail, filing 338 bills in 43 states, according to the Brennan Center.

Those bills would remove excuse requirements for requesting mail-in ballots, extend the time voters could fix problems with their ballot and create or expand permanent absentee lists so that voters don’t have to request a mail-in ballot every election.

In a recent survey by the Pew Research Center, Republicans and Democrats said the expansion of early voting and mail voting helped President Joe Biden win in November. But a Public Policy Institute of California study found that steps to make voting easier in 2020 most likely had little partisan effect, and if there was one, it was a slight benefit for Republicans.