Defeat to Donald Trump looms over Nikki Haley. So why stay in the race?

Republican presidential candidate Nikki Haley is staring down another resounding loss to Donald Trump, this time in her home state of South Carolina. But Ms Haley has vowed not to quit, raising speculation about the ambitions of her long-shot campaign.

Three days before the state primary, a crowd of Republican voters in North Augusta, South Carolina, packed shoulder-to-shoulder in to the sunny top floor of a municipal building for a Nikki Haley campaign event.

As the state's former governor, Ms Haley gave the gathering an assured and newly combative stump speech. She made frequent and pointed jabs at her rival and the Republican frontrunner, former President Donald Trump - a tactic she had long avoided.

"He was literally unhinged," she said at one point, remarking on his victory speech after the New Hampshire primary. "He's obsessed with himself," she added later.

In this room at least, Ms Haley's pitch and criticism of the former president were landing. Her jokes received loud laughs, the applause breaks were long, and at least a dozen voters in attendance told the BBC they were all in on Ms Haley.

"She's got an outstanding record," said supporter Holt Moran. "She's just the perfect person."

But again and again, when asked if Ms Haley had a chance of winning the primary - or even another Republican contest down the line - each voter seemed to wince before saying no.

"Unfortunately not," Mr Moran said.

Despite her publicly sunny outlook, the packed events, and beaming crowds, it will be nearly impossible for Ms Haley to find a path to the nomination. She has lost every contest to Mr Trump so far, and is likely to do so again on Saturday, this time in her home state.

Polls show the former UN ambassador is trailing by nearly 30 points in South Carolina and her odds are even worse in votes to come.

Barring a dramatic and unforeseen twist, Mr Trump will - for the third time in a row - be his party's nominee. But Ms Haley has so far shown no signs of quitting.

So is Ms Haley's enduring campaign a quixotic exercise or - as she says - a principled stand against Mr Trump? Or is she perhaps playing a longer game and laying the groundwork for future political ambitions?

With pundits and commentators - and her own party leadership - claiming she is wasting Republicans' time and money, Ms Haley has struggled to defend her resolve.

In Greenville this week, in what her campaign had billed as a "state of the race address," Ms Haley gave a 26-minute speech devoted entirely to why she still sought the Republican nomination.

"I refuse to quit," she said. "South Carolina will vote on Saturday. But on Sunday, I'll still be running for president."

There, and in most public appearances since, Ms Haley has cast her enduring campaign as an act of principle, a decision meant to give Republicans an alternative to Mr Trump or President Joe Biden - who she contends are "the most disliked politicians in America".

"There are 70% of Americans who don't want another Biden-Trump rematch and 60% of Americans who think Biden and Trump are both too old," one of Ms Haley's spokeswomen, Olivia Perez-Cubas said. "They [voters] deserve a better choice."

Friends and allies of Ms Haley have insisted that her public remarks are sincere, and that she is focused solely on this year's Republican nomination.

"When you talk to her in private, she says I'm sticking with this," said Jenny Sanford-McKay, South Carolina's former first lady and Ms Haley's friend. "The opportunity for her is now."

Some contend Ms Haley is continuing as a candidate in case Mr Trump, who faces numerous criminal and civil legal challenges, suddenly had to bow out of the race.

But Republican strategists have also raised another theory: perhaps Ms Haley is looking four years ahead, with an eye toward the next presidential election in 2028.

If that is the plan, Ms Haley's current campaign would provide her a significant head start, functioning as a nationwide rehearsal for her messaging and fundraising. Even as she trails Mr Trump, Ms Haley has assembled teams in at least a dozen states and planned a seven-figure ad buy ahead of Super Tuesday on 5 March, when Republicans in 16 states will vote.

"People will remember her, and that she was a solid candidate," Ron Bonjean, a political strategist, said.

Deep-pocketed donors are helping her ongoing efforts by pouring millions of dollars into her campaign, with several saying publicly they see her as a competent counter to Mr Trump's chaos.

In January alone, campaign officials said Ms Haley raised $16.5m (£13m) - her largest monthly total.

That money seems to correlate with the energy on the ground. Almost in spite of the steady drum beat of bad polling, on the campaign trial this week Ms Haley appeared relaxed and upbeat, drawing out her tightly-rehearsed stump speeches with new riffs, laughing at her own jokes.

The voters in attendance seemed energised too, both about Ms Haley and about leaving Mr Trump behind.

"She's a real path forward," supporter David Hood said at a campaign event in Georgetown on Thursday. "Trump is an embarrassment."

Another voter, Tim Ferguson said he would be proud to cast his ballot for Ms Haley, after twice voting for Mr Trump. "I've always said, after I vote for him I go home and take a shower - I don't feel right," he said.

But just outside the bubble of Ms Haley's campaign and her future prospects is the reality of the current Republican Party, with a base still very much devoted to Mr Trump. And, despite sending Ms Haley to the statehouse and then to the governor's mansion two times over, South Carolina is proving no different.

In Lexington County, where Ms Haley lived with her young family when she launched her political career, residents mostly shrugged when asked about their former neighbour's campaign for president.

"I don't care where somebody's from," said Gregg Moore, who owns an antique store in downtown Lexington. "Mr Trump is from New York and Florida. I'm not from New York and Florida, but he has what this country needs and therefore I'm voting for him."

Mr Moore, like other Lexington County voters who spoke to the BBC, was not particularly critical of Ms Haley. Most said simply she could not compete with the former president, who they believed had proved his mettle in the White House.

And it is not just South Carolina's voters who are lining up behind Mr Trump. The state's Republican lawmakers and leadership have as well.

"We all know it's Trump's party at this point, right?" South Carolina Republican strategist and Trump critic Chip Felkel said.

That may be true. But for now, as long as there's money left to spend, Ms Haley can simply carry on. After all, he said, "what has she got to lose?".