Donald Trump is facing growing pressure to condemn an Ultimate Fighting Championship (UFC) competitor who used a White House appearance to push a sexist, racist and transphobic conspiracy theory about former first lady Michelle Obama.

At a UFC event on the south lawn on Sunday, the US president’s 80th birthday, Josh Hokit, a fighter, shouted into the microphone in front of Trump: “Michelle Obama is a man. Am I right, America?”

Trump appeared to show a half-smile seconds after Hokit’s slur, CNN reported, while some in the audience burst into a laughter. The false claim can be traced to far-right echo chambers online. The president himself has a history of making offensive remarks.

Hokit’s outburst was widely denounced at the event, which critics had already derided as a tacky and vulgar debasement of the White House, ahead of the 250th anniversary of independence. Donna Brazile, a former interim chair of the Democratic National Committee, said: “Michelle Obama’s legacy speaks for itself. Shame on the vile comments from that UFC fighter.”

Sunny Hostin, a lawyer, journalist and co-host of The View on the ABC network, addressed the controversy on Monday’s show. “For a long time – and the roots are in slavery – Black women have been slurred and made to feel that they were unattractive, made to feel that they were masculine, made to feel that they didn’t have the femininity that a white woman would have,” she said.

“There is this intersectionality between racism and sexism that was on full display at the White House. The crowd laughed at the statement and the president of the United States smirked and never addressed what was said. That is beneath the dignity of the office of the president of the United States, and it’s beneath the dignity of the American people.”

The White House did not respond to a request for comment but even Trump allies called for the president to break his silence on the issue.

Dave Portnoy, the founder of Barstool Sports, who endorsed and voted for Trump in the 2024 presidential election, said on Wake Up Barstool on Fox Sports 1: “There was one moment I do think Trump has to denounce, and anybody associated with it has to denounce. And that’s that crazy fighter guy … he won the fight, he took the microphone, and he made a derogatory comment about Michelle Obama.”

Portnoy added: “When you have that on the White House lawn on an event you put on, I don’t care what you think about the Obamas or anything, that has to be an immediate denounce. I have no problem with the event. I guess you run that risk because these guys are lunatics. But that was the only thing. Trump should denounce it.”

Dana White, the UFC impresario, told Time magazine in a text message: “I understand that the Obamas are public figures, but I’m completely against saying nasty and false things about people’s families. Everyone knows my position on free speech but I hate that kind of nonsense.”

Robert Griffin III, a former American football quarterback who does not support Trump, but has called for understanding of his supporters, wrote on X: “What a disgrace. It takes a really small man to use his biggest moment to attack a woman by calling her a man. Especially with the history behind calling black women men.”

But some on the right defended Hokit. Dan Bongino, a rightwing podcaster and former deputy director of the FBI under Trump, tweeted: “The pearl clutching over a joke, made by a UFC heavyweight known for his post fight stand up comedy acts, is next level hypocrisy.

“The same people moaning and clawing at their faces over it have absolutely no problem calling President Trump and his supporters “nazis,” and “fascists,” so I’ll pass on the faux outrage. Thanks. And have a splendid day!”

Michelle Obama and her husband, former president Barack Obama, are regularly the targets of racist abuse. Earlier this year Trump shared a video clip on his Truth Social platform that depicted the couple as apes then deleted it after an outcry.