Nikki Haley, a leading contender for the Republican presidential nomination in 2024, has turned on Donald Trump, saying she was "disgusted" with the former president.
Haley, Trump's ambassador to the United Nations, said he had "let us down" and "fallen so far". The former governor of South Carolina has long been seen as a potential Republican nominee in four years, and started a political action committee last month.
Her comments set up a clear fissure in the Republican party as other would-be candidates, including Ted Cruz and Marco Rubio, looked set to seek backing from Trump's followers. Both senators are expected to vote to acquit Trump at the end of his impeachment trial.
In an interview with Politico, Haley disclosed that she had not spoken to Trump since his supporters stormed the US Capitol on January 6. She did not believe Trump himself would run for the nomination in 2024, claiming he was no longer a "viable" candidate.
"I don't think he's going to be in the picture," she said. "I don't think he can. He's fallen so far. We need to acknowledge that he let us down. He went down a path he shouldn't have, and we shouldn't have followed him. We shouldn't have listened to him, and we can't let that ever happen again."
Haley expressed particular condemnation of Trump's treatment of Mike Pence, his vice-president, whom he called a "coward" on January 6. She said: "I am so disappointed in the fact that [despite] the loyalty and friendship he had with Mike Pence, that he would do that to him. Like, I'm disgusted by it."
Haley was a high-profile member of Trump's cabinet, and regarded as a star of his administration for her defence of his America First policy on the world stage. She unexpectedly resigned in late 2018 but was given a glowing public send-off by Trump in the Oval Office, leading to speculation about a future presidential run.
She said she still believed impeaching Trump was a "waste of time" and that the end of his political career was enough of a consequence.
"I think his business is suffering at this point," she said. "I think he's lost any sort of political viability he was going to have.
"I think he's lost the things that really could have kept him moving."