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Donald Trump.
Trump had previously made the claims on Twitter following the election. He defeated Hillary Clinton, the Democratic nominee, soundly in the Electoral College, but lost the popular vote by nearly 3 million ballots.
Trump has yet to produce any evidence to back up his claim, and it was judged untrue by numerous fact-checkers and voting officials.
Senate Majority Whip John Cornyn, a Texas Republican who was present in the meeting, said he was surprised by the voter fraud claims.
"I didn't pay a lot of attention to it," he said, according to Politico. "I was ready to move onto some policy issues. I didn't anticipate that discussion."
Speaking with Fox Business host Maria Bartiromo Tuesday, former Arkansas Gov. Mike Huckabee, a prominent Trump supporter, said he was confused why the president brought up the claims again.
"I have no evidence whatsoever, and I don't know that anyone does, that there were that many illegal people who voted and frankly it doesn't matter," he said. "He's the president, and whether 20 million people voted, it doesn't matter anymore; he's the president, and I'm not sure why he brought it up."
And Sen. Lindsey Graham of South Carolina, speaking with NBC News, said the assertion harms Trump's "ability to govern."
"To continue to suggest that the 2016 election was conducted in a fashion that millions of people voted illegally undermines faith in our democracy, it's not coming from a candidate for office, it's coming from the man who holds the office," Graham said. So I am begging the president, share with us the information you have about this or please stop saying it."
"As a matter of fact I'd like you to do more than stop saying it, I'd like you to come forward and say 'having look at it, I am confident the election was fair and accurate and people who voted, voted legally,'" he continued. "Cause if he doesn't do that this is going to undermine his ability to govern this country."