Charleston, South Carolina - After promising she would never run against Donald Trump, former South Carolina Governor Nikki Haley appears poised to announce a bid for president in 2024 – and that hasn't gone unnoticed by her prospective primary rival.

Haley is expected to make a formal campaign announcement on February 15 in Charleston, South Carolina, setting up a potential showdown with her former ally Donald Trump.

Ex-president Trump, who announced in December he would run on the Republican ticket again in 2024 after losing his second bid to Joe Biden in 2020, responded to the news by sharing a past video of Haley on Truth Social.

In the clip, which dates back to April 2021, a reporter asks, "If [Trump] runs again in 2024, will you support him?"

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"Yes," Haley answers, before the reporter asks, "If he decides that he's going to run, would that preclude any sort of run that you would possibly make yourself?"

"I would not run if President Trump ran," the anti-abortion, anti-trans politician replies.

"Nikki has to follow her heart, not her honor. She should definitely run!" Trump wrote on his Truth Social page on Wednesday.

Haley was the US ambassador to the United Nations for two years during the Trump administration. If she announces a 2024 presidential bid, she would be the first Republican candidate to do so apart from her former boss.

Former VP Mike Pence and ex-Secretary of State Mike Pompeo are reportedly mulling 2024 challenges, as is far-right Florida Governor Ron DeSantis.