After winning South Carolina's Republican primary vote on Saturday, Trump is firmly on track to secure the party's nomination in the coming weeks.

But rival Nikki Haley's better-than-expected showing in South Carolina exposed weaknesses on Trump's flank, particularly among more traditional Republicans and moderate voters.

Some experts say those voters are more likely to be alienated by Trump's hardline policies on immigration and other issues and his racist rhetoric. The possibility of Trump being convicted on some of the numerous state and federal charges he faces may also deter some of those voters.

Trump has recently described migrants as "poisoning the blood" of the country. Over the weekend, he claimed at an event that Black voters like him because of his multiple indictments, comments that triggered a swift backlash.

Haley won about 40% support in South Carolina after taking about 43% of the vote last month in the New Hampshire primary. In both cases, she was bolstered by independents and some Democrats who took part in the primary to back her over Trump.

Haley insists she will fight on and argues that a large swath of Republicans continue to reject Trump.

"There are huge numbers of voters in our Republican primaries who are saying they want an alternative," she wrote in a fundraising pitch to supporters on Sunday.

Haley says she will stay in the race through "Super Tuesday" on March 5, when 15 states and one U.S. territory will award delegates to the Republican Convention. Her campaign said on Sunday she had raised a fresh $1 million since her loss in South Carolina.

Trump lost the 2020 election to Biden, a Democrat, in part because Biden was able to pull white suburban voters, who are often more moderate than rural voters, away from him.

Biden won independents by a sizable gap, 54% to 41%. Millennial and Gen Z voters also favored Biden.

Those same segments of the electorate have gravitated to Haley in South Carolina and New Hampshire, raising the question of whether Trump will be able to reel in those voters once she exits the race.

"If you're Donald Trump, you've got to wonder: Am I going to be able to carry those people through? Are they going to show up on Election Day for me in November?" said Dave Wilson, a South Carolina-based Republican strategist.

"There is a lot of courting that will have to be done of that vote in other states if South Carolina plays itself out as a kind of microcosm of America as a whole."

So far, Trump hasn't seemed interested in adjusting his rhetoric to court those voters, nor does his campaign appear to be believe they are an issue.

"I've never seen the Republican Party so unified as it is right now," Trump said after his South Carolina win.

Asked for comment, Trump's campaign shrugged off Haley's vote share, saying she's "the candidate of choice for liberal Democrats and Never Trumpers."

Trump "is the strongest person to take back the White House," said spokesperson Steven Cheung, pointing to polls that show Trump leading Biden in several battleground states that could determine the election.

Trump's message on the stump over the last several months has been consistent: hardline stances on issues such an immigration and foreign policy that appeal most strongly to his conservative base, which has rewarded him by propelling him to easy victories.

But voters in a general election differ greatly from those in the Republican primary.

The most recent Reuters/Ipsos poll, taken earlier this month, showed Trump with a 37%-34% edge over Biden, suggesting he could draw enough support to prevail. But 22% of respondents said they wanted another choice or would not vote, a group that likely will remain fluid until election day.

At a rally in Rock Hill, South Carolina on Friday, Trump accused Haley of staying in the race to damage his chances against Biden.

"All she's trying to is inflict pain on us so (Democrats) can win in November," he said.

Wilson was skeptical Trump would be able to modify his combative and polarizing approach.

"You're asking Donald Trump to be something other than Donald Trump if you ask him to kind of change his messaging or change himself. He doesn't do that," he said. "But there are a different group of voters who are looking for a different style of president."

According to exit polls conducted by Edison Research, Haley edged out Trump among college-educated voters and claimed 70% of those who described themselves as moderates.

Those voters are among those most likely to blame Trump for his role in the Jan. 6, 2021 assault on the U.S. Capitol, said Adolphus Belk, a professor of political science at Winthrop University in South Carolina.

"Trump does really well with people were strong Republicans or kind of independent, but lean heavily Republican," Belk said. "He's going to have a challenge in the general election with moderate voters who cannot get over what happened three years ago."

(Reporting by James Oliphant in Washington and Nathan Layne in Columbia, South Carolina; Editing by Kieran Murray and Lincoln Feast)

By James Oliphant and Nathan Layne