A commissioner on the Federal Elections Commission (FEC) sent President Trump a letter Tuesday demanding that he provide evidence to back up his claims of voter fraud in last year's elections.

“You have alleged that hundreds of thousands of voters were bused from Massachusetts to New Hampshire to vote illegally on Election Day 2016,” Ellen Weintraub wrote in the letter, which was first reported by The Washington Post.

Trump has suggested massive voter fraud helped Democrat Hillary Clinton Hillary Diane Rodham ClintonHillicon Valley: FBI chief says Russia is trying to interfere in election to undermine Biden | Treasury Dept. sanctions Iranian government-backed hackers The Hill's Campaign Report: Arizona shifts towards Biden | Biden prepares for drive-in town hall | New Biden ad targets Latino voters FBI chief says Russia is trying to interfere in election to undermine Biden MORE beat him in the popular vote by nearly 3 million votes. More recently, Trump has also blamed voter fraud for former Republican Sen. Kelly Ayotte Kelly Ann AyotteBottom line Bottom line Bottom Line MORE's defeat in her New Hampshire reelection bid.

“Our democracy depends on the American people’s faith in our elections,” Weintraub, a Democrat who was appointed by former President George W. Bush in 2002, continued.

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“Your voter-fraud allegations run the risk of undermining that faith. Facts matter, Mr. President. The American people deserve to see your evidence.”

Weintraub noted Trump’s claims of voter fraud could ultimately result in more restrictive election laws.

“Because of the trust that Americans place in their Presidency, some lawmakers around the country may be tempted to rely on your words and move forward with unwarranted voter restrictions,” she said. "Indeed, this could result in deterring or preventing American citizens from voting.

“Given the already disappointingly low turnouts in recent American elections, I would hope that everyone can agree that encouraging every citizen to vote should be a priority.”

Weintraub added she is personally contacting Trump after a statement she tweeted in February went unanswered.

“I didn’t get any response,” she told the Post. "I tweeted it, and he likes Twitter, so I thought maybe he would see it.”

Trump allegedly told a bipartisan group of senators that “thousands” of people from Massachusetts illegally cast ballots in New Hampshire during the 2016 race, causing Ayotte to lose.

Trump repeatedly warned of voter fraud as a White House hopeful, doubling-down on the idea after winning the Electoral College in November but not the popular vote. But Trump hasn't offered any proof of his claims of widespread voter fraud.