WASHINGTON, United States, April 1, 2026 (BSS/AFP) - President Donald Trump on Tuesday signed an order seeking to crack down on mail-in voting, escalating his push to restrict a popular way of casting ballots in US elections.

Trump's executive order follows repeated attacks by the 79-year-old Republican on US elections, based on his disproven conspiracy theories about supposed cheating by his Democratic opponents.

It was unclear whether Trump has authority to impose the measures and legal challenges are almost certain, with a possible final decision being left to the Supreme Court.

"We will sue," Marc Elias, a prominent Democratic Party elections lawyer, said. "I don't bluff and I usually win."

Polls show that Trump's Republican Party faces a serious threat of losing its narrow control of Congress in the midterm elections in November, particularly in the House of Representatives, the lower chamber.

If Democrats win, they have signaled they will block Trump's agenda and could move to impeach him.

Trump has been pressing hard for measures that experts believe would likely lower turnout, with potentially huge consequences in parts of the country where elections are decided by razor-thin margins.

On signing the executive order Tuesday, Trump repeated his evidence-free talking points painting US elections as dysfunctional.

"The cheating on mail-in voting is legendary. It's horrible," Trump said, calling Democratic leaders in Congress "corrupt."

"They want to be able to cheat," he said.

Trump's false claim to have won the 2020 election against Joe Biden makes him the first president in modern history to have refused a peaceful transfer of power.

No evidence has been produced by any credible authority that the 2020 vote or any other was impacted by cheating.

Trump himself has frequently voted by mail-in ballots, as recently as this month in Florida.

A review by the Brookings Institution of decades of data collated by the right-wing Heritage Foundation turned up only 39 cases of fraud among more than 100 million ballots cast in 32 elections spanning three decades.

Tuesday's order came as his Republican Party has failed to pass a more far-reaching set of voting restrictions called the "SAVE America" act.

In addition to requiring a photo ID to cast a ballot, the bill would also require proof of citizenship to register to vote, a demand that experts say would push millions of people without passports or birth certificates from being able to participate.

An analysis by the Brennan Center found that more than 21 million Americans lack easy access to such documents.

Trump's push for federal election overhauls has also run up against constitutional concerns.

Under the US Constitution, states retain broad control over the administration of elections.