Florida Gov. Ron DeSantis suspended his campaign for the Republican presidential nomination Sunday, ending a bid that began as the best-funded and most high-profile challenge to former President Trump but fizzled over the course of a year.

He endorsed Trump, saying in a video posted to social media that it was now clear that “a majority of Republican primary voters want to give Donald Trump another chance.”

DeSantis said he and his team had “prayed and deliberated” about how to move forward after he finished a distant second in last week’s Iowa caucuses.

“I can’t ask our supporters to volunteer their time and donate their resources if we don’t have a clear path to victory,” DeSantis added. “Accordingly, I am today suspending my campaign.”

“Fire sale on all Ron DeSantis merch today!” Gov. Gavin Newsom, who predicted DeSantis would not be the Republican nominee when the pair debated on Fox News in November, gleefully wrote on X, formerly Twitter.

DeSantis received 21.2% of the vote in Iowa, well behind Trump’s 51% and just two points ahead of former South Carolina Gov. Nikki Haley, who won 19.1%.

DeSantis said he disagreed with Trump over his handling of the pandemic and his “elevation” of chief medical advisor Anthony Fauci, but argued that the former president “is superior to the current incumbent, Joe Biden.”

In an statement Sunday afternoon, Trump said he was “very honored” to have DeSantis’ endorsement.

“It is now time for all Republicans to rally behind President Trump to defeat Crooked Joe Biden and end his disastrous presidency,” the campaign statement read. “Nikki Haley is the candidate of the globalists and Democrats who will do everything to stop the America First movement.”

In his farewell video, DeSantis also took a dig at Haley, who has steadily risen in the polls.

“We can’t go back to the old Republican guard of yesteryear, a repackaged form of warmed-over corporatism that Nikki Haley represents,” DeSantis said.

“He ran a great race, he’s been a good governor, and we wish him well,” Haley said at a New Hampshire event Sunday afternoon, minutes after DeSantis exited the race. “Having said that, it’s now one fella and one lady left. … All the fellas are out except for this one. And this comes down to, what do you want? Do you want more of the same or do you want something new?”

DeSantis’ sudden departure from the contest effectively makes Tuesday’s New Hampshire primary a head-to-head battle between Haley and Trump. But DeSantis, several other Republican dropouts and a collection of lesser-known candidates will all still appear on Tuesday’s ballot.

Haley has staked her campaign on the Granite State, hoping to slow the Trump juggernaut by winning over moderate New Hampshire voters. Polling over the last two months showed her gaining on the former president, and by early January she appeared to be within striking distance. But after her less-than-impressive showing in Iowa last week, Haley’s New Hampshire outlook began to look grimmer.

Earlier on Sunday, the closely watched Suffolk University/NBC 10 Boston/Boston Globe tracking poll had Trump finishing with 55% of the vote to Haley’s 36%. In the same poll released Sunday, DeSantis was a distant third, polling at just 6%. Even if all DeSantis voters switched to Haley, the shift would not be enough to eliminate Trump’s lead.

DeSantis’ decision to drop out effectively makes the primary a two-person race, but will not greatly benefit Haley, said Dante Scala, a political science professor at the University of New Hampshire.

“It makes the hill even steeper,” he said. “Most of those DeSantis voters are not going to Haley. Some will stay with DeSantis anyway. Of those remaining, I’ve got to think the split will favor Trump. That makes thing a little steeper for Haley on Tuesday.”

Scala marveled at how quickly Trump appeared to be securing the GOP nomination. “How rapidly Trump is wrapping things up is remarkable,” Scala said.

A year ago, DeSantis appeared to represent a formidable challenge to Trump and surpassed him in many polls of potential Republican primary voters.

A mid-February UC Berkeley IGS/Los Angeles Times poll of California Republicans, for example, found DeSantis leading Trump 37% to 29% in the state, which sends the largest delegation to the Republican National Convention. At the time, Republicans were still smarting from the defeats they suffered in the 2022 midterm elections, which many in the party blamed on Trump, and many voters were open to DeSantis’ argument that he could offer Trump-like policies without the attendant baggage.

But the strength of that argument waned as memories of the midterm losses began to fade. At the same time, three other developments undermined DeSantis’ hopes: Criminal indictments of Trump caused many Republican voters to rally around the former president; Biden’s standing in polls started to slip, blunting the argument that Republicans needed someone other than Trump to defeat the incumbent; and Trump pummeled DeSantis with attacks that the Florida governor largely left unanswered, fearing that attacking back would alienate the Trump supporters he needed.

When he was riding high, polls showed that much of DeSantis’ support came from Republicans skeptical of Trump — college-educated voters and more moderate Republicans who disliked the former president’s style and some of his policies. But DeSantis aimed his appeals primarily at Trump’s core supporters, who make up the largest part of the Republican primary electorate. For a brief time, that approach appeared to work — conservative voters were attracted to DeSantis because of his issue stands and his pugnacious attacks on liberals and culture-war targets, while moderates saw him as the best bet to beat Trump.

But the strategy only worked so long as DeSantis seemed to be beating Trump. Once his poll numbers started to decline, many of those moderate voters pulled away. Meantime, most conservatives seemed uninterested in anyone other than Trump.

That set in motion a downward spiral that DeSantis proved unable to reverse. Between January and July, he lost roughly half his support in the average of national polls maintained by FiveThirtyEight, a polling aggregator. In California, Trump retook the lead by mid-May and never relinquished it.

Over the course of the fall, DeSantis’ aides fought bitterly — sometimes publicly — over strategy, and the candidate often appeared to be flailing as he sought a way forward. DeSantis’ campaign was plagued by a series of blunders, starting with his campaign launch, which took place on Twitter and was interrupted by technical problems.

A former staffer at Never Back Down, the super PAC that was effectively the backbone of DeSantis’ campaign, was deeply disappointed by the Florida governor’s decision to end the campaign. But the person, who was granted anonymity to speak candidly, questioned some of the organization’s spending decisions.

“He’s amazing. He did the 99 counties,” the staffer said, referring to DeSantis’ barnstorming of Iowa. “He’s not lazy. He’s a hard worker. I truly wish he was the guy.”