After President Donald Trump last week repeated the false claim that massive voter fraud kept him from winning the popular vote in November, his senior adviser Stephen Miller on Sunday attempted to defend the statement ― without providing any evidence.

“It’s very real, it’s very serious,” he said on ABC News’ “This Week.”

Host George Stephanopoulos repeatedly pressed Miller to back up his claim, but Miller wouldn’t.

“We can talk about it more in the future,” Miller said. “The reality is, we know for a fact, you have massive numbers of noncitizens registered to vote in this country. Nobody disputes that.”

White House senior advisor doubles down on unsubstantiated NH voter fraud claims: “Voter fraud is a serious problem in this country” pic.twitter.com/DC6lVPQznz — ABC News (@ABC) February 12, 2017

State officials who monitor voting processes have no evidence of significant voter fraud in the United States. However, Miller said he would continue to defend Trump’s claim.

“I’m prepared to go on any show, anywhere, any time and repeat it and say the president of the United States is correct, 100 percent,” he said.

Stephanopoulos ended the segment after several more minutes of Miller falsely asserting that voter fraud “is a fact.”

“You have provided zero evidence of the president’s claim that he would have won the popular vote if 3 to 5 million illegal immigrants hadn’t voted, zero evidence for either one of those claims,” Stephanopoulos said. “Thanks a lot for joining us this morning.”

Trump and his advisers continue to claim — without evidence — that “millions” of people voted illegally. The president even promised “a major investigation” into the matter, but has yet to launch one.

Trump reportedly brought up voter fraud on Thursday while meeting with a group of senators to discuss his Supreme Court nominee, Neil Gorsuch. He insisted that former Sen. Kelly Ayotte (R-N.H.), who is helping Gorsuch with his confirmation process, would have won re-election and that he would have won New Hampshire “if there hadn’t been voter fraud.”

Fergus Cullen, the state’s former GOP chairman, called Miller’s claim that residents from neighboring states rode buses to vote in New Hampshire “delusional.”

Miller makes false #magicbus claim, offers no proof. Delusional. There are no bused-in voters #nhpolitics https://t.co/dFa6lZw6Ux — Fergus Cullen (@FergusCullen) February 12, 2017

And Tom Rath, former New Hampshire attorney general and GOP delegate, tweeted that the “baseless” claims were “shameful.”

Let me as be unequivocal as possible-allegations of voter fraud in NH are baseless,without any merit-it's shameful to spread these fantasies — Tom Rath (@polguru) February 12, 2017

This was at least the second time Trump has reportedly mentioned the false claim during a meeting with lawmakers on Capitol Hill. Just days after his inauguration in January, he told congressional leaders that 3 million to 5 million “illegals” voted for his Democratic opponent, Hillary Clinton.

This article has been updated with comments from Cullen and Rath.