One by one, Donald Trump’s defeated rivals for the 2024 Republican nomination took the stage to sing his praises at the party’s convention on Tuesday night. From his box just above the convention floor, Trump smiled as he watched his former opponents Nikki Haley, Ron DeSantis, and Vivek Ramaswamy voice their full support for his candidacy.

If there were any doubts that this was Trump’s party, Tuesday’s programming put them to rest.

“I’ll start by making one thing perfectly clear: Donald Trump has my strong endorsement, period,” said Ms. Haley, the former UN Ambassador who posed the strongest challenge to Trump earlier this year. She mentioned that Trump had asked her to speak at the event in Milwaukee in the name of “unity.”

“For the sake of our nation, we have to go with Donald Trump,” she told the crowd. Although Ms. Haley had previously said in May that she would vote for Trump, her headline speech on Tuesday was her most direct endorsement of the Republican nominee yet. When she declared her endorsement, Trump stood and clapped.

Ms. Haley’s arrival was not universally welcomed in the arena. There was a noticeable intake of breath as she acknowledged that she and Trump had their differences. Some Republicans have struggled to forgive her for launching an aggressive campaign against their favored candidate. Late in the race, she questioned whether Trump had the mental stamina to serve as president.

A smattering of boos greeted her as she took the podium, though they were soon drowned out by cheers and chants. Gregory Switzer, a conservative activist from Texas, believed she deserved the booing. Matt Bumela, a delegate from Washington state, who had predicted the booing, said, “She stayed in that race a lot longer than she needed to and dragged out the inevitable. And said things about Trump that were negative all the way up to the end.”