Florida Governor Ron DeSantis has dropped out of the 2024 presidential race and endorsed Donald Trump.
He quit ahead of the Republican primary election in New Hampshire, where he was polling in the single digits.
Mr DeSantis was once considered a strong contender for the party’s nomination – but on Sunday he said he did not “have a clear path to victory”.
Nikki Haley, Mr Trump’s last remaining challenger, said she was the “only one” able to beat US President Joe Biden.
Ms Haley will go head-to-head with Mr Trump in New Hampshire on Tuesday, the second in a series of state-by-state contests to pick a Republican nominee for the November general election.
In a nearly five-minute long video on X, formerly Twitter, released on Sunday afternoon, Mr DeSantis said his campaign had “left it all out on the field”.
“If there was anything I could do to produce a favourable outcome – more campaign stops, more interviews – I would do it,” he added, as he ended his seven-month campaign.
The Florida governor said he was endorsing Mr Trump, who is the clear frontrunner after winning the first contest in Iowa with 51% of the vote.
Mr DeSantis said it had become clear that a majority of Republican voters “want to give Donald Trump another chance”.
He acknowledged “disagreements” with the former president, but said Mr Trump was “superior” to Mr Biden, who is almost certain to be the Democratic nominee in November’s general election.
“I signed a pledge to support the Republican nominee, and I will honour that pledge,” Mr DeSantis said.
There were loud cheers when Mr Trump made his first comments about Mr DeSantis’s withdrawal and endorsement to a room in New Hampshire full of supporters on Sunday afternoon.
Later, addressing an audience at a rally, Mr Trump described his former opponent as a “really terrific person”, adding: “He ran a really good campaign, it’s not easy.”
Mr DeSantis had presented himself as the Republican candidate who could deliver Mr Trump’s populist agenda without the drama or baggage.
But one of the speakers at the event, Florida Representative Matt Gaetz, referred to him as “diet Trump”.
And several supporters of Mr Trump told the BBC they liked the Florida governor but felt this was not the right time for him.
Lynne Mason, 60, said she thought Mr DeSantis’s campaign was “a little weak” and she had “expected more from him”. Mr Trump, she added, was the “only person at this time who can save this country”.
BethAnne Tatro, another local backing Mr Trump, agreed. “I think that President Trump has proven, from being in office previously, that he can do this again and get things back on track”.
After Mr DeSantis’ announcement, the Trump campaign called on all Republicans to rally behind Mr Trump, slamming his former UN Ambassador as “the candidate of the globalists and Democrats who will do everything to stop the America First movement”.
Mr DeSantis also took a swipe at Ms Haley, calling her a member of “the old Republican guard of yesteryear – a repackaged form of warmed-over corporatism”.
Ms Haley, a former South Carolina governor, responded by insisting she was the conservative candidate – the “only one” – who could beat Mr Biden.
“There’s two people in this race,” she told CNN in New Hampshire. “That’s what we wanted all along, and we’re going to keep going.”
Mr DeSantis narrowly finished ahead of Ms Haley in last week’s Iowa caucuses with 21% of the vote, compared to her 19%, both well behind Mr Trump.
At the time, Mr DeSantis framed the second-place finish as a victory, but it was a major disappointment after he had spent the bulk of his time and resources courting its conservative evangelical voters.
His departure from the race allows Mr DeSantis to avoid an embarrassing potential third-place finish in New Hampshire to Ms Haley, who has focused far more of her resources in the state.
But a person familiar with Mr DeSantis’ election night plans in New Hampshire was completely caught off guard by the news of his exit.
The source told the BBC the campaign had just confirmed plans with them on Saturday for their election night celebration this coming Tuesday.
Chris Ager, the state committee chair of New Hampshire’s Republican Party, told the BBC that “the race has been moving toward a one-vs-one between Trump and Haley for a while”.
“This makes it so,” he added.