Columbia, South Carolina - Presidential hopeful Nikki Haley tried to fire up the crowd at a South Carolina barbecue joint – even though the polls say Donald Trump is set to smoke her in the Republican presidential primary in her home state.

"Head to head, Trump does not beat Joe Biden. I defeat Biden," the former South Carolina governor told supporters on Thursday, as steam rose from piles of fried chicken and pulled pork on a buffet nearby.

The ex-UN ambassador is now the sole challenger to her former boss, with Haley (51) hoping a home advantage will help her in the Palmetto State's primary on February 24.

Her message is aimed at more moderate Republicans and wavering Democrats - focusing on the "chaos" of Trump's first term and bashing both the 77-year-old and 81-year-old Biden as too old for a second term.

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She faces an uphill battle. A Washington Post/Monmouth University poll released Thursday showed Trump leading Haley by 58 percent to 32 percent.

Still, supporters at Doc's Barbecue restaurant said she could still win, describing the race as a choice between a "Republican and a fascist."

"I just love her moral fiber," said supporter Sarah Rock. "She's not going to have criminal issues, and I think she is what our country needs."

Her rival's shadow is never far away, though. Outside the Haley rally, a pickup truck flying pro-Trump flags drove up and down the road in a seemingly endless loop.

For weeks, Trump has portrayed himself as the presumptive Republican nominee as he seeks an extraordinary comeback to the White House.

Trump steamrollered the first two Republican votes in Iowa and in New Hampshire, where Haley had hoped to appeal to its more independent voters.

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Unlike Florida Governor Ron DeSantis, Haley has refused to bow out and let Trump focus on battling Biden. She points to a series of polls showing that she would be more likely than Trump to defeat him in a hypothetical match-up.

Trump has, therefore, been forced to keep fighting in South Carolina, using resources that he'd rather use on his national campaign – and the multiple legal cases he faces.

Haley has also walked into a series of controversies during the campaign, including when she refused to say recently that slavery was the cause of the American Civil War.

The issue was a pertinent one in South Carolina, with a large Black population that Democrats – who hold their primary in the state on Saturday – are also trying to woo.

But her persistence in staying in the race has gotten under Trump's skin.

In a bad-tempered victory speech in New Hampshire, Trump surrounded himself with leaders from South Carolina, including the current governor, in a show of strength and lashed out at Haley for refusing to quit.

He has also resorted to racially-charged barbs, repeatedly referring to Haley, the daughter of immigrant parents, by her first name Nimarata - on one occasion purposefully misspelling it on social media.

The move was reminiscent of his frequently calling former President Barack Obama by his middle name, Hussein, as part of his false smears that Obama was born outside the United States and ineligible to be president.

Haley said she had "no personal problems" with Trump but insisted that she would fight on in South Carolina and beyond so long as she kept closing in on Trump's vote share.

"This is a state we have worked really hard on," she told reporters after her rally. "We're not going anywhere."

Haley and Trump will duke it out in South Carolina on February 24.