Florida Governor Ron DeSantis has suspended his Republican US presidential campaign just before the New Hampshire primary and endorsed Donald Trump, ending a White House bid that failed to meet expectations that he would emerge as a serious challenger to the former president.

“It’s clear to me that a majority of Republican primary voters want to give Donald Trump another chance,” he said in a video posted on X on Sunday.

New Hampshire’s primary, the first in the United States, comes on Tuesday.

DeSantis derided former UN Ambassador Nikki Haley, long his closest rival for second place in the primary race, saying Republicans “can’t go back to the old Republican guard of yesteryear, a repackaged form of warmed-over corporatism that Nikki Haley represents.”

DeSantis entered the 2024 presidential contest with major advantages in his quest to take on Trump, and early primary polls suggested he was in a strong position to do just that.

He and his allies amassed a political fortune well in excess of $100m and he boasted a significant legislative record on issues important to many conservatives like abortion and the teaching of race and gender issues in schools.

Such advantages did not survive the reality of presidential politics in 2024.

From a high-profile announcement that was plagued by technical glitches to constant upheavals to his staff and campaign strategy, DeSantis struggled to find his footing in the primary. He lost the Iowa caucuses – which he had vowed to win – by 30 percentage points to Trump.

And now, DeSantis’s political future is in question after he suspended his presidential bid following just one voting contest. The 45-year-old is term-limited as Florida’s governor.

DeSantis was widely expected to be a serious challenger to Trump.

Acknowledging the threat, Trump went after the Florida governor viciously in the months leading up to DeSantis’s announcement of his candidacy in May, and continued to pound him on the campaign trail, on social media and in paid advertising in the months that followed.

Yet many of DeSantis’s problems may have been his own doing.

Fuelled by his dominant Florida re-election in 2022, DeSantis sidestepped tradition by announcing his presidential campaign on X, in a conversation on the social media site with CEO Elon Musk. The site failed repeatedly during the conversation, making it all but impossible to hear his opening remarks as a presidential candidate.

In the subsequent weeks and months, DeSantis struggled to connect with voters on a personal level.

He irked some New Hampshire Republican officials in his campaign’s inaugural visit to the state by declining to take questions from voters, as is tradition in New Hampshire. And later, uncomfortable interactions with voters in other states were caught on camera as well.

More serious financial challenges emerged over the summer.

By the end of July, DeSantis had laid off nearly 40 employees in a move designed to cut roughly one-third of his campaign payroll. The cuts came shortly after public filings revealed that he was burning through his substantial campaign coffers at an unsustainable rate.

Some people looking for a Trump alternative backed Haley, the former diplomat and South Carolina governor who gained popularity among many Republican donors, independent voters and the so-called Never Trump crowd.

DeSantis and Haley frequently attacked each other in debates and in advertising, often more directly than they went after Trump.

As internal financial concerns mounted, DeSantis turned aggressively to an allied super PAC to handle basic campaign functions such as organising campaign events, advertising and an expansive door-knocking operation.

Federal law does not allow campaigns to coordinate directly with super PACs.

In December, a non-partisan government watchdog group filed a complaint with the Federal Election Commission, citing reporting by The Associated Press and others, alleging that the degree of coordination and communication between DeSantis’s campaign and the Never Back Down super PAC crossed a legal line.

DeSantis denied any wrongdoing and called the complaint “a farce”.

Still, the steady stream of negative developments leading up to the opening primary contests undermined the confidence of DeSantis’s donor network, which was supposed to be a major strength, and would-be supporters at the ballot box. As his polling numbers stagnated, DeSantis and his allies pulled back on their multistate strategy and focused virtually all of his resources on Iowa’s opening caucuses.

After leaving the 2024 presidential contest, DeSantis now refocuses his attention on the rest of his second and final term as Florida’s governor, which ends in January 2027.