Former Republican presidential candidate Nikki Haley has said she plans to vote for Donald Trump, her former opponent and boss, in the 2024 US presidential election.

Ms Haley, who once served as Mr Trump's United Nations ambassador, was the last of his major rivals to drop out of the party primary contest, in early March.

At the time, she did not endorse him but urged him to earn the votes of the millions who had supported her.

On Wednesday, in her first public remarks since leaving the race, she said Mr Trump "has not been perfect", but that President Joe Biden "has been a catastrophe".

Anti-Trump Republican voters largely coalesced behind Ms Haley's presidential bid earlier this year, and her dormant candidacy is still picking up support more than two months after she left the race.

She won more than 20% of the vote in at least two state primary elections over the past fortnight.

The Biden campaign is seeking to woo these Haley Republicans, a mix of moderate and college-educated independent voters who could help swing the election toward the Democrat. Mr Biden argues that Mr Trump has repeatedly "made it clear he doesn't want" voters who supported her.

Mr Trump, who has mocked his ex-cabinet member as a "bird brain", was angered by her prolonged primary challenge and recently shot down rumours that she was under consideration to be his vice-presidential running mate.

Speaking on Wednesday before a gathering at the conservative Hudson Institute think-tank in Washington DC, Ms Haley maintained the criticisms of both parties she made in her campaign.

But she reserved her strongest words for the incumbent.

Mr Biden, she said, oversaw a "debacle" in Afghanistan, "did nothing to deter the invasion" of Ukraine and, most recently, "threw Israel to the wolves".

"As a voter, I put my priorities on a president who's going to have the backs of our allies and hold our enemies to account, who would secure the border, who would support capitalism and freedom, who understands we need less debt not more debt," she said.

"Trump has not been perfect on these policies but Biden has been a catastrophe. So I will be voting for Trump."

But the former South Carolina governor did not call on her supporters to do the same.

"I stand by what I said in my suspension speech," she told the audience.

"Trump would be smart to reach out to the millions of people who voted for me and continue to support me, and not assume that they're just going to be with him, and I genuinely hope he does that."

The former president has not reached out in any capacity, she noted.

Speculation is now likely to grow over whether Ms Haley will formally mend ties with Mr Trump and endorse him.

Wednesday's remarks will also raise the spectre of a Trump-Haley Republican ticket in November, a move that would be met with fierce disapproval among some Trump backers.

Republican campaign strategist John Connors told the BBC that Ms Haley is "clearly sending a signal" to Mr Trump.

"This could be a signal from Haley to start talks to entertain a deal with Trump to join his ticket and get another look for VP," he said.

"It's worth a look because it would open up more fund-raising avenues from major donors, who are sitting on the sidelines right now, and also pull more college-educated female voters and never-Trump voters back into the fold."

Mr Connors added: "Trump-Haley - it would be a tough ticket to beat."

Additional reporting from Brandon Drenon