Nikki Haley was barely known outside her native South Carolina before Donald Trump tapped her as ambassador to the United Nations back in 2017.
But Haley used the high-profile post to cultivate an image as a plain-speaking conservative, and a reputation for standing up to her boss -- whom she is now challenging for the 2024 Republican presidential nomination.
Republicans with ambitions for the highest American office have been keeping their powder dry until now, wary of getting a bloody nose from the man who wrote the book on no-holds-barred political brawling.
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Haley, 51, appears to be made of sterner stuff, releasing a campaign launch video Tuesday in which she did not mention the 76-year-old Trump by name but said it is "time for a new generation of leadership."
Her message was clear: she is readying for a bare-knuckled nomination fight, regardless of who she is up against.
As UN envoy, Haley -- who previously served for six years as South Carolina's governor -- was unafraid to speak her mind, often in fairly undiplomatic language.
She was the face of the White House to the world on everything from North Korean denuclearization to the war in Syria.
Speculation about Haley's political future had been building since she left Trump's cabinet in 2018, and she now starts an uphill battle to become her party's White House candidate.
The daughter of Indian immigrants, who was raised as a Sikh but identifies as Christian, Haley was the face of diversity in a cabinet criticized for being too white.
She 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.
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 understandably, eyebrows were raised when Trump chose Haley -- who had little foreign policy experience -- as Washington's voice at the United Nations.
Born in 1972 in Bamberg, South Carolina, Nimrata "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, killing nine parishioners.
She was also a fierce defender of Israel, and a ferocious critic of Russia.
Since leaving government, Haley's praise of the Trump presidency has been offset by her criticism of his personal conduct, including his involvement in the 2021 attack on the US Capitol.
"We need to acknowledge he let us down," she said, referring to Trump's actions leading up to the insurrection.