MIAMI, April 13 -- President Donald Trump entered to a standing ovation and cheers from a crowd of thousands attending a UFC event on Saturday night, shaking hands with supporters against a backdrop of fans waving his trademark MAGA hats.

Just as Trump entered, he greeted podcast host Joe Rogan, who sat to the right of the president. On the other side of Trump sat Elon Musk, billionaire and chief of the Department of Government Efficiency. Trump, who accented his dark suit with a bright yellow tie, pumped his fist in the air, prompting cheers to strains of "Taking Care of Business."

He brought along several members of his administration and White House team, including Health and Human Services Secretary Robert F. Kennedy Jr., FBI Direct...