Former President Donald Trump falsely claimed on social media Sunday that a crowd at a Michigan rally for Vice President Kamala Harris last week “DIDN’T EXIST,” “nobody was there” and that photos of the event were fabricated by artificial intelligence.

In the days following President Joe Biden’s announcement that he would step aside as the Democratic nominee, conspiracy theorists and far-right influencers have promoted a number of falsehoods targeted at the Harris campaign. But Trump’s repeating of the false claims about the crowd size and photos, with multiple posts on his Truth Social platform, is a notable escalation.

“Has anyone noticed that Kamala CHEATED at the airport? There was nobody at the plane, and she ‘A.I.’d’ it, and showed a massive ‘crowd’ of so-called followers, BUT THEY DIDN’T EXIST!” the Republican nominee for president wrote on social media. Trump continued, “She’s a CHEATER. She had NOBODY waiting, and the ‘crowd’ looked like 10,000 people! Same thing is happening with her fake ‘crowds’ at her speeches. This is the way the Democrats win Elections, by CHEATING.”

There were in fact thousands of people gathered when the plane arrived at the airport, and there is no evidence that news organizations altered photos using artificial intelligence. There is also no evidence that Harris, or Democrats more broadly, have cheated to win elections, despite Trump’s repeated false allegations that the 2020 presidential election was “rigged.”

David Plouffe, a senior adviser for Kamala Harris for President, expressed concern on X, the social media site formerly known as Twitter, about Trump’s comments.

“These are not conspiratorial rantings from the deepest recesses of the internet,” Plouffe wrote. “The author could have the nuclear codes and be responsible for decisions that will affect us all for decades.”

The event last week at an airport hangar in Detroit was live-streamed, widely attended by the media including The Washington Post, and many attendees posted their own pictures and video showing a packed venue. Local news outlet MLive estimated that 15,000 people filled the hangar and that attendees spilled out into the tarmac.

Mallory McMorrow, a Michigan state legislator who was at the event tweeted photos, noting that “you can just see the throngs of people outside.”

On Sunday, the Harris campaign rejected Trump’s comments, writing on the social media site X, “This is an actual photo of a 15,000-person crowd for Harris-Walz in Michigan.”

Trump, the GOP nominee for president, for years has been focused on crowd size as a metric of success. He has repeatedly taken to social media to boast about how the size of crowd he could draw and last week asserted at a news conference that “nobody’s spoken to crowds bigger than me.”

Trump has previously claimed that the audience for a speech he gave in Washington on Jan. 6, 2021, the day a mob stormed the U.S. Capitol, eclipsed the numbers who attended Martin Luther King Jr.’s “I Have a Dream” speech despite photographic evidence that it did not.

Trump has regularly been challenged by fact-checkers and opposition groups for elevating discredited allegations, repeating unfounded rumors as fact, or grabbing onto conspiracies, especially when under political threat.

In 2016, he falsely claimed President Barack Obama was not born in the United States and did not attend Columbia University, that Trump’s taxes were audited because he is Christian, that vaccines are connected to autism and that climate change is a hoax.

In 2020, he refused to advocate for wearing masks during the coronavirus pandemic, and promoted unfounded claims about purported risks.

The Washington Post Fact Checker team in January 2021 noted that it had logged “30,573 untruths during his presidency — averaging about 21 erroneous claims a day.”

Trump’s focus on crowd size also has become something that the Harris campaign has used to poke fun at Trump about — while at the same time bragging about their own crowds.

Democratic vice-presidential nominee Tim Walz at a Friday night rally with Harris, looking at an audience in Arizona that Democrats estimated at more than 15,000, quipped, “It’s not as if anybody cares about crowd sizes or anything.”

On Sunday afternoon, the Harris campaign released a statement describing a crowd of “more than 12,000 Nevadans” at a rally over the weekend — “one of the largest political rallies in modern Nevada political history” — and then described previous audiences as including “14,000+ in Philadelphia, 12,000+ in Eau Claire, and 15,000+ in both Detroit and Arizona.”

And at a fundraising event in San Francisco on Sunday, Harris appeared to address Trump’s social media accusations indirectly.

The energy around the country is “undeniable,” Harris said, adding, “The press and our opponents like to focus on our crowd size, and yes the crowds are large.” But even better, she said, attendees are signing up for volunteer shifts by the thousands.