Haley has quit at just right time to step on to a bigger stage

Nikki Haley departs her post in much the same fashion as she went about her business at the United Nations: on her own terms and in a blaze of glowing headlines.

For the past 18 months she has somehow managed to perform two high-wire balancing acts. She has pushed Donald Trump’s unilateralist, America First agenda, while keeping international diplomats onside, winning admirers among the foreign missions based in New York.

At the same time, she has been the star of a rambunctious administration, generating positive coverage and sparking speculation of a 2020 White House run – while avoiding the fate of Steve Bannon, the strategist jettisoned by a president jealous of the column inches he attracted.

So when Ms Haley announced her resignation yesterday, it arrived in business-like style. There had been no leaks, briefings or hints before Mr Trump trailed the news in a tweet. The ambassador herself did not even offer much of a reason for her departure beyond a vague suggestion that it was time for a change.

She was clear on one thing, however: she will not be running in 2020. No surprise there. Taking on an incumbent president would be political suicide.

But what about 2024?

Ms Haley’s surprise departure means she leaves with her political stock sky high. She has been the face of American foreign policy for the past 18 months, leapfrogging above an invisible secretary of state (remember Rex Tillerson anyone?) and a national security adviser in HR Mcmaster who never gained the president’s trust.

Her polling numbers are the type to make billionaire donors salivate as they think about life after Trump, but those numbers could not have lasted.

The hawkish appointments of Mike Pompeo and John Bolton mean Ms Haley no longer has the foreign policy floor to herself. But she goes out on a high and at the age of 46 has time for a second and third act. Which was probably her plan all along.