Former President Donald J. Trump said in an address to an evangelical group that he had suggested starting a sports league for migrants to fight one another.

Appearing at the Faith & Freedom Coalition’s conference in Washington on Saturday, Mr. Trump described migrants with the dehumanizing terms he often uses to refer to them, saying they were “tough,” “come from prisons” and are “nasty, mean.”

Mr. Trump then said that he had suggested to Dana White, an ally of the former president’s who is the chief executive of the Ultimate Fighting Championship, “Why don’t you set up a migrant league of fighters?”

He continued, referring to the U.F.C.: “And then you have the champion of your league — these are the greatest fighters in the world — fight the champion of the migrants? I think the migrant guy might win! That’s how tough they are.”

Mr. Trump said that Mr. White “didn’t like the idea too much.” But, he added, “It’s not the worst idea I’ve ever had. These are tough people.”

Mr. White, asked about Mr. Trump’s comment at a U.F.C. event on Saturday, confirmed that the former president had made the proposal, but said, “It was a joke, it was a joke. I saw everybody going crazy online. But yeah, he did say it.”

The Biden campaign denounced Mr. Trump’s comments, attacking what it called “a rambling, confused tirade,” at what it said was intended to be “a conference for Christian values.”

“Trump’s incoherent, unhinged tirade showed voters in his own words that he is a threat to our freedoms and is too dangerous to be let anywhere near the White House again,” Sarafina Chitika, a spokeswoman for the Biden campaign, said in a statement.

Mr. Trump has made immigration a central part of his platform in the 2024 presidential election, as it was in his two previous campaigns. He has pledged to carry out sweeping raids and to use military funds to erect camps to hold undocumented detainees. He has also escalated his rhetoric against migrants, at times using language that invokes the racial hatred of Hitler by describing migrants as “poisoning the blood of our country.”

“Fantasies about cage matches are a distraction from the very real plans Trump and his team are making to deport millions of people who have lived here for decades and the resulting inflation, joblessness and economic devastation,” said Douglas G. Rivlin, a spokesman for America’s Voice, an immigrant-rights advocacy group that has been tracking the escalation of Republican rhetoric on the issue. “Republican politicians are going to find that hard to defend while campaigning this year.”

Jazmine Ulloa contributed reporting.