WASHINGTON —  Nikki Haley abruptly resigned on Tuesday as the US ambassador to the United Nations, in the latest departure from President Donald Trump’s often shifting national security team.

Meeting Haley in the Oval Office, Trump said she had done a "fantastic job" and would stay on to the end of the year.

"She told me probably six months ago that ’I want to take a little time off’," Trump told reporters.

A successor will be named "in the next two or three weeks," he said.

However, Haley was coy on her reasons for quitting, saying only that it was "important to understand when it’s time to stand aside" after a string of challenging jobs.

US media reports quoted administration officials saying privately that Haley’s departure was a surprise even to Secretary of State Mike Pompeo.

In a statement to journalists at the White House that lasted a few seconds, Pompeo called her a "great partner." He then refused to take questions.

US media speculated that Haley has ambitions for running against Trump in the primaries ahead of the 2020 elections, where she might be seen as a more moderate Republican alternative to his turbulent and often divisive presidency.

But she quashed the rumour. "No I’m not running," she said.

Trump and Haley went out of their way to emphasise that the resignation was taking place on amicable terms -- something far from the norm in the administration’s turbulent first two years.

But while Washington insiders questioned whether Haley’s departure signaled a new round of palace intrigue, a more prosaic explanation for the move was that she needs to earn a serious private sector salary.

Her 2018 government ethics financial disclosure shows her with debts that included a mortgage of more than $1 million.

Trump later said he has five people on his shortlist to replace Haley, including his former deputy national security advisor Dina Powell, who is Egyptian American. He did not give the other four names he has in mind.

While Richard Grenell, the current US ambassador to Germany and former US spokesman at the UN, was not on the shortlist, Trump said he was willing to consider him for the post.

Earlier, the president had quipped his own daughter Ivanka would make a "dynamite" replacement, an idea she quickly tamped down.

‘Divisive’

A former governor of South Carolina, Haley took the UN job with little experience in foreign policy, but quickly became the full-throated voice for the Trump agenda.

Haley has pressed for a hard line on Iran, justified US cuts to foreign assistance and earlier this year led the United States in bolting from the UN Human Rights Council, accusing it of bias against Washington and close ally Israel.

The daughter of Indian immigrants, Haley had long been seen as a rising star in the Republican Party, which has eagerly sought female and ethnic minorities to broaden the appeal beyond its traditional white demographic.

Haley, whose given name was Nimrata Randhawa, was elected governor in 2010 of deeply Republican South Carolina and, during the 2016 campaign, had criticised Trump over his remarks on immigrants before their political reconciliation.

She got high marks from UN Secretary General Antonio Guterres, who spoke of his "deep appreciation."

Haley is the latest official to resign from a turbulent White House, where Trump is already on his third national security adviser and second secretary of state before even the midterm elections.

She insisted that she was going out on a high and would remain loyal to Trump. — AFP