WASHINGTON, Feb 1 (Reuters) - Former South Carolina Governor Nikki Haley will kick off her campaign for the 2024 Republican presidential nomination this month, squaring off against her one-time boss, Donald Trump, two sources familiar with her plans said on Wednesday.

The move would make her just the second declared Republican candidate and could set the stage for a more combative phase of the campaign, potentially putting her in the sights of the pugnacious former U.S. president.

Haley's campaign sent an email to supporters on Wednesday inviting them to a Feb. 15 event in Charleston. There she will declare her candidacy, the sources said.

South Carolina is expected to host one of the first Republican nominating primaries in 2024 and will play an important role in picking the eventual candidate.

The daughter of two Indian immigrants who ran a successful clothing store in a rural part of the state, Haley has gained a reputation in the Republican Party as a solid conservative who has the ability to address issues of gender and race in a more credible fashion than many of her peers.

She has also pitched herself as a stalwart defender of American interests abroad, having served as U.S. ambassador to the United Nations under Trump from 2017 to 2018. During that time, the United States pulled out of the Iran nuclear deal, which was inked under Democratic President Barack Obama and was highly unpopular among Republicans.

One Haley associate said she chose to launch her campaign this early to try to grab voters' attention and shake up a race that had so far been dominated by Trump and Florida Governor Ron DeSantis, who has not yet declared whether he will run.

Many key Republican donors and elected officials in South Carolina have been looking for alternatives to Trump amid concerns about his electability, according to conversations in recent weeks with more than a dozen party officials and strategists.

Several prominent Republicans, including Haley and U.S. Senator Tim Scott, opted to skip a Trump campaign appearance in Columbia on Saturday, which was intended to showcase his support in the state.

Scott, often considered a presidential contender himself, will kick off a "listening tour focused on Faith in America" in Charleston a day after Haley's event, according to a campaign advisory. He will then swing through Iowa, another key early voting state.

Trump told reporters on Saturday that Haley had called him to say she was considering a run and that he told her "go by your heart if you want to run," according to multiple media reports.