Former president Donald Trump pressed ahead with his ongoing effort to erode confidence in U.S. elections during his debate Tuesday night with Vice President Kamala Harris, repeating his false claim that he won the 2020 vote, refusing to condemn the violence of Jan. 6, 2021, and claiming without evidence that Democrats are helping millions of noncitizens cast ballots this fall.

Trump twice declined to say whether he had any regrets about the attack on the U.S. Capitol, when a mob of Trump supporters, egged on by the president, stormed the building in an effort to block the final certification of Joe Biden’s 2020 victory.

“Ashli Babbitt was shot by an out-of-control police officer that should have never, ever shot her,” Trump said about a pro-Trump rioter who was killed while attempting to enter the House chamber that day. “Nobody on the other side was killed.” He did not elaborate on what he meant by “the other side.”

In addition to Babbitt, three police officers died in the immediate aftermath of the riot — one who collapsed that day while battling rioters and two others who took their own lives in the days to follow. Three other people died as a result of medical emergencies suffered during the riot.

Trump also said he was being “sarcastic” when he recently said he lost in 2020 “by a whisker” — a line that drew condemnation from far-right influencers such as Nick Fuentes and threatened Trump’s support among those who have repeated his false claims that the election four years ago was stolen.

“Look, there’s so much proof, all you have to do is look at it,” Trump said. No such proof ever surfaced in dozens of lawsuits that year, and Trump’s aides have testified that he was repeatedly told by allies that he had lost.

Trump on Tuesday suggested fraud will mar this year’s vote, specifically claiming without evidence that Democrats are encouraging noncitizens to cast ballots. The false claim has become a regular talking point among right-wing influencers, including X owner Elon Musk. Only U.S. citizens can vote in federal elections; noncitizen voting is extremely rare.

“We have to have borders, and we have to have good elections,” he said. “Elections are bad. And a lot of these illegal immigrants coming in, they’re trying to get them to vote.”

The remarks underscored the possibility that Trump may not accept the result in November if he loses. The former president has said he believes the only way he can lose is if the Democrats cheat.

Trump’s debate remarks come just days after he posted on social media his plans to jail people “involved in unscrupulous behavior,” related to voting in this year’s election, suggesting without evidence that the election could be stolen from him. Trump’s post prompted widespread condemnation from election officials, who said such rhetoric could provoke violence.

Harris seized on Trump’s refusal to accept his defeat four years ago and predicted he would do the same if he loses this year, too.

“Donald Trump was fired by 81 million people. So let’s be clear about that,” Harris said during the debate as Trump shook his head. “And clearly he is having a very difficult time processing that. But we cannot afford to have a president of the United States who attempts, as he did in the past, to upend the will of the voters in a free and fair election.”

Harris also condemned Trump’s recollections of the violent events of Jan. 6.

“I was there and on that day, the president of the United States incited a violent mob to attack our nation’s Capitol, to desecrate our nation’s Capitol,” she said. “On that day, 140 law enforcement officers were injured and some died. And understand, the former president has been indicted and impeached for exactly that reason.”

Trump boasted of the admiration he has won from Hungarian Prime Minister Viktor Orbán, an ally of Russian President Vladimir Putin who has consolidated power by curtailing press freedom and choking off independent institutions.

“Let me just say about world leaders, Viktor Orbán, one of the most respected men, they call him a strong man,” Trump said. “He’s a tough person, smart prime minister of Hungary.”

Harris was prepared with a retort to that, citing Trump’s comments that he wants to be a dictator, but only on his first day in office.

“He exchanged love letters with [North Korean leader] Kim Jong Un,” Harris said, before addressing Trump directly.

“It is absolutely well known that these dictators and autocrats are rooting for you to be president again,” she said, “because they’re so clear they can manipulate you with flattery and favors.”

Karen DeYoung contributed to this report.