Nikki Haley, the former governor of South Carolina and ambassador to the United Nations, has announced her candidacy for president, becoming the first major challenger to former President Donald Trump for the 2024 Republican nomination.

The announcement, delivered via video, marks a sea change for the former Trump cabinet official, who said two years ago she would not challenge her former boss for the White House in 2024.

But he changed his mind in recent months, citing, among other things, the country’s economic woes and the need for a “generational change,” a nod to Trump’s age of 76.

Ms Haley, 51, is the first in a long line of Republicans expected to launch 2024 campaigns in the coming months.

They include Florida Gov. Ron DeSantis, former Vice President Mike Pence, former Secretary of State Mike Pompeo and Sen. Tim Scott of South Carolina.

President Joe Biden has said he intends to seek re-election in 2024, halting any fight for the Democratic nomination.

Ms Haley has regularly boasted of her record of defying political expectations, saying, “I’ve never lost an election and I’m not going to start now.”

If elected, Ms. Haley would be the nation’s first female president and the first American president of Indian descent.

The daughter of Indian immigrants, Ms. Haley grew up enduring racist taunts in a small South Carolina town and has long referenced that impact in her personal and political arc.

She was an accountant when she launched her first bid for public office, defeating the longest-serving member of the South Carolina House of Representatives in 2004.

Three terms later and with little recognition statewide, Ms. Haley mounted a long shot campaign for governor against a large field of seasoned politicians.

He racked up a number of high-profile endorsements, including from incumbent South Carolina Gov. Mark Sanford and former Alaska Gov. Sarah Palin, a tea party favorite.

With her victory in 2010, Ms. Haley became the first minority and female governor of South Carolina, and the youngest in the country at 38 years old.

He won a speaking slot at the 2012 Republican National Convention and gave the Republican response to President Barack Obama’s State of the Union address in 2016.

In a statement, Taylor Budowich, a spokesperson for Trump’s super PAC, said Ms Haley was “just another career politician.”

“He started out as a Never Trumper before resigning to serve in the Trump administration,” he said.

“Then he quit early to go raise money at corporate meetings. Now, she tells us that she represents a ‘new generation’. It sure sounds like more of the same, a career politician whose only fulfilled commitment is to herself.”