Washington (AFP) - Nikki Haley prided herself on being the last challenger standing between the "chaos" of Donald Trump and the 2024 Republican White House nomination. Now her dreams of becoming America's first female president have evaporated for now.

Following a slew of losses in the United States' drawn out, state-by-state primary season, including defeats to Trump in almost all 15 state contests waged on "Super Tuesday," the former governor of South Carolina announced Wednesday she was suspending her presidential campaign.

The 52-year-old was little known outside her native South Carolina before Trump tapped her as ambassador to the United Nations back in 2017.

Haley used the high-profile post to cultivate an image as a plain-speaking conservative.

Speculation about Haley's presidential ambitions had been building since she left Trump's cabinet in 2018.

And even as the ex-president eclipsed her in this year's primaries, she held out, demanding voters be given a choice beyond what will now almost certainly be a rematch of the 2020 election.

Other Republicans with ambitions for the highest American office have largely bowed down to Trump and his capture of the party, wary of his hardcore, far-right base.

Haley meanwhile ran a campaign that criticized the "ranting, raving and chaos" of the twice-impeached, criminally indicted Trump, urging voters that it was "time for a new generation of leadership."

Her sustained campaign raised questions for the upcoming general election, where the ex-president is set to face off with Joe Biden.

While Trump is backed by passionate supporters ready to ignore his attack on the 2020 election and four ongoing criminal cases, it remains to be seen whether middle-of-the-road Republicans who favored Haley will commit to Trump in November.

As UN envoy, Haley -- who previously served for six years as South Carolina's governor -- was known for speaking her mind, often in undiplomatic language.

She was the face of the White House to the world on everything from North Korean denuclearization to the war in Syria.

'Not a fan'

The daughter of Indian immigrants, Haley was raised as a Sikh but identifies as Christian. She proved to be the face of diversity in a cabinet that was overwhelmingly white.

Haley was not exactly on the Trump train from the get-go -- she endorsed Florida Senator Marco Rubio during the Republican primary race in 2016 before backing Senator Ted Cruz of Texas.

Indeed, she called Manhattan property baron Trump "everything a governor doesn't want in a president," and just weeks before the election, admitted she was "not a fan" of the candidate.

So eyebrows were raised when Trump chose Haley -- who had little foreign policy experience -- as Washington's envoy at the United Nations.

Born in 1972 in Bamberg, South Carolina, Nimarata "Nikki" Randhawa -- a mother of two -- rose quickly in the southern state's politics, serving in its House of Representatives from 2005 to 2011, when she was elected governor.

Her conservative views and outspoken but collegial style were popular in her home state.

She got headlines in 2015 by supporting the removal of the Confederate flag from the state house after a white gunman opened fire at a black church in Charleston, killing nine parishioners.

She has also been a fierce defender of Israel and critic of Russia.

During the campaign she flexed her foreign policy chops, launching a fusillade of attacks against Trump over his encouragement of Russian President Vladimir Putin to invade NATO allies in Europe.

Haley made history as the first woman to win a Republican presidential primary contest, prevailing in Vermont and the US capital Washington.

She conspicuously did not endorse Trump in Wednesday's brief concession speech, saying it was up to him to "earn the votes" of those who did not support him in the primaries.

But in a sign she is keeping her own options open -- including a possible eye on the 2028 presidential race -- she did not repeat her attacks of Trump, instead highlighting her campaign themes including supporting Ukraine and opposing socialism.

As for the race she ran, "I have no regrets," she said.