Photo: Damon Winter/The New York Times; Video: By THE ASSOCIATED PRESS

Gov. Chris Christie of New Jersey is awkwardly adapting to a new role: Donald J. Trump’s yes man.

During Mr. Trump’s victory news conference on Tuesday night in Florida, Mr. Christie stood behind him during the business mogul’s entire speech, offering the constant nods, a gaze of admiration and unrelenting affirmation usually reserved for a political spouse.

Mr. Christie smiled. He clapped. He called him, deferentially, Mr. Trump. He fawningly declared that Mr. Trump’s candidacy was “not a campaign. It’s a movement.” He enthused about the billionaire’s “Super Tuesday” victories, calling them “important for our country.”

It was an arresting image, far from Mr. Christie’s original vision of himself as this stage of the Republican presidential contest: as a nominee, not a sidekick.

But he is embracing the job with gusto.

When Mr. Trump explained the exodus of jobs from states like New Jersey, Mr. Christie’s face broke into a mischievous and somewhat embarrassed smile. He mouthed the word “no,” but quickly returned to smiling.

“Chris,” Mr. Trump said, “understands the problem.”

For the next 20 minutes, Mr. Christie stood ramrod straight, tie askew, just off to the side, taking it all in.

Mr. Christie did not appear fully comfortable, perhaps unsure of whether he should remain onstage. But remain he did, effectively taking the place of Mr. Trump’s entire family, who did not appear in the television frame.

That privilege was reserved for Mr. Trump and his new constant companion.

Alan Rappeport contributed reporting.