Mary Trump, the estranged niece of former President Donald Trump, says a particular moment in her uncle’s poorly received debate performance against Vice President Kamala Harris caused irreparable “narcissistic injury.”

During an appearance on MSNBC’s Deadline: White House On Wednesday, Mary Trump told moderator Nicolle Wallace that her uncle suffered a “crushing defeat” in his first and possibly only presidential debate with Harris on Tuesday. The majority of polls and pundits suggested that Harris won the debate.

Wallace pointed to a moment during a debate when Harris appeared to rattle Trump after taking jabs at his rally crowd who reportedly left the event early, prompting the former president’s niece, a psychologist, to say her uncle would “never get over” the bruise to his ego.

“It was a narcissistic injury that he will never really get over,” said Mary Trump. “He will continue to fight it, even if he never says another word about it. That’s how thin-skinned he is, that’s how incredibly fragile his ego is.”

“So that was one of the most gratifying things about Vice President Harris’ brilliant performance last night,” she continued. “She was able to have substantive conversations about the issues while also provoking him so exquisitely.”

Newsweek reached out to Donald Trump’s office via email on Wednesday evening for comment.

During the debate, the former president appeared to lose his composure after Harris urged the audience to “attend one of Donald Trump’s rallies” to witness a series of bizarre remarks by Trump and his supporters, who left the event early “out of exhaustion and boredom.”

“People aren’t going to their rallies, there’s no reason to,” a defensive Trump said in response. “People aren’t leaving my rallies. We have the biggest rallies, the most incredible rallies in the history of politics.”

Mary Trump predicted during her MSNBC appearance that Donald Trump’s responses to Harris’ attacks would only “get worse,” implying that the former president would have no choice but to “try to dominate from a position of extraordinary weakness.”

The former president’s niece also warned that her uncle and his allies would try to “cheat” in November if they feared Harris would likely hand him his second consecutive presidential election defeat.

“Given his crushing defeat last night, he knows he may be going down,” Mary Trump said. “And if he feels that’s the case, he’s going to take us all down with him, and we have to be vigilant.”

“It means that he and his entourage and his supporters in the Republican Party are going to do their best to cheat in this election,” she added. “We’ve already seen it, he’s already rigging the election in advance by challenging results we don’t even have yet.”

Trump campaign communications director Steven Cheung said Newsweek previously said that “Trump Derangement Syndrome is a serious problem and some people like (Mary Trump) should get themselves checked out.”