Donald Trump has picked up another endorsement from Nikki Haley’s home state of South Carolina, with representative Nancy Mace backing the former US president in this year’s Republican presidential primary.

Ms Mace had stayed out of the 2024 Republican primary as two fellow South Carolinians – former governor Ms Haley and senator Tim Scott – entered the race last year.

On Monday, a day ahead of the New Hampshire primary, Ms Mace told the Associated Press that she was backing Mr Trump over Ms Haley, who lives in her congressional district and supported her in 2022 against a Trump-backed challenger.

Ms Mace said: “I don’t see eye-to-eye perfectly with any candidate. And until now I’ve stayed out of it.

“But the time has come to unite behind our nominee.”

The South Carolina Republican’s backing comes as Mr Trump angles to bolster his dominance thus far in Republican balloting, following his record-setting win last week in the Iowa caucuses.

Over the weekend, Mr Trump was joined by a slew of South Carolina leaders as he campaigned in New Hampshire, seen as yet another blow from South Carolina against Ms Haley.

Florida governor Ron DeSantis’ departure from the race on Sunday leaves Ms Haley as the main Republican candidate remaining to challenge Mr Trump.

New Hampshire votes on Tuesday, but South Carolina’s primary is in a month, and the state’s Republican leadership has largely already lined up behind the former president as he seeks a rematch with Joe Biden in the national election this autumn.

Ms Mace’s endorsement means that Mr Trump has secured four of the state’s six Republican US house members, with representatives Russell Fry, Joe Wilson and William Timmons also behind him, while Ralph Norman is backing Ms Haley and Jeff Duncan is saying he is not endorsing before the primary.

Just two years ago, Ms Mace and Ms Haley were aligned in a congressional primary that tested Mr Trump’s heft in South Carolina, where his own 2016 presidential primary win helped cement his nomination.

After the January 6 attack on the US Capitol in 2021, Ms Mace – who had just been sworn in as a representative for the first time – went on TV to criticise Mr Trump for his role in the day’s events, saying the president’s accomplishments in office “were wiped out in just a few short hours”.

Mr Trump had been trying to overturn the 2020 presidential election after he lost to Democrat Joe Biden and in a rally encouraged his backers to storm the Capitol, telling them they needed to “fight like hell”.

He responded by calling Ms Mace “an absolutely terrible candidate” and soliciting “any interest from good and smart America First Republican Patriots” to run against a list of sitting House Republicans, including Ms Mace, whom he endorsed for her first run in 2020 and who worked for his 2016 campaign.

When Katie Arrington, who unsuccessfully sought the seat in 2018, launched her 2022 bid against Ms Mace, she had Mr Trump’s “complete and total endorsement”.

During a pre-primary rally in South Carolina, Mr Trump called Ms Mace “crazy” and “a terrible person”.

Ms Haley, meanwhile, stumped with Ms Mace, as she had in 2020, helping raise money and appearing in a television ad on her behalf, calling her a “fighter”.

But the two have not spoken since last year, when Ms Mace’s name was floated as a possible running mate choice for Mr Trump, should he win the Republican nomination.

Ms Mace said she felt Mr Trump is the better option this year.

“Donald Trump’s record in his first term should tell every America how vital it is he be returned to office,” she said.