The winner of the South Carolina primary has gone on to be the Republican presidential nominee for 30 straight years — and that could be bad news for Mitt Romney, who suddenly finds himself in a real battle with Newt Gingrich in Saturday's vote.

Polls suggest support for the former House speaker has surged since his fiery performance in Thursday night's candidates' debate, giving him a slight lead over the former Massachusetts governor and a good chance of grabbing all 25 of the state’s delegates.

At a Saturday morning event in Boiling Springs, Gingrich predicted a "tremendous victory" and told supporters that a vote for him was the "only way to go stop a Massachusetts moderate" from attaining the Republican nomination.

The two other candidates — former Pennsylvania senator Rick Santorum and Texas congressman Ron Paul — appear to have stalled in the polls and are not expected to have much of a showing

The Romney camp was downplaying talk of victory, instead emphasizing that their candidate has performed beyond expectations in the conservative state where he finished a distant fourth four years ago. Nevertheless, a loss would come as a blow to Romney, who seemed to have great momentum following his victory in the New Hampshire primary. 

Dead heat

Romney acknowledged at a morning event in Spartanburg that he was in a dead heat with Gingrich for the prized state. 

"There is every indication this is going to be a very close race," he said alongside the state's governor, Nikki Haley, who endorsed him.

Romney’s political fortunes seem to have turned. Following his New Hampshire win, he could boast of being the first Republican candidate to capture both Iowa and New Hampshire, and he was leading in the polls in South Carolina. He had also picked up an endorsement from Jon Huntsman, the former Utah governor who dropped out of the race.

However, over the last 10 days, things have gone a little sour.

His performance at the debate sponsored by Fox News last Sunday was judged by many to be poor — mediocre at best. He stumbled badly over questions about releasing his tax returns, and by Thursday’s CNN debate, he still didn’t seem to have an adequate answer.

Lots of bad news

That was just a part of the bad news he received on Thursday: The Iowa Republican party declared Santorum had actually received more votes in the state's caucus vote; and Texas Gov. Rick Perry quit the race to support Gingrich, again narrowing the hard-right vote splitting.

But Gingrich got his own dose of trouble on Thursday: His ex-wife Marianne claimed in an interview with ABC News that Gingrich had sought an "open marriage" that would include his then-lover and now wife Callista.

However, the allegations have had little impact on his popularity in the heavily conservative state, suggesting voters may have already reconciled themselves to Gingrich's history of infidelities.

Romney is still struggling for acceptance with two important factions: the evangelical/religious right and the Tea Party, which has become a force within the Republican ranks.

Tim Scott, a South Carolina Republican congressman and Tea Party favourite, said he believes the organization will have a "masterful" influence on Saturday’s primary.

"When you think about the Tea Party’s influence in our state already — what you see is a number of candidates all appealing to the Tea Party," he said.

But Scott, who had not yet endorsed a candidate, suggested Romney may be being judged unfairly by some of the members, and that when it comes to being conservative, it’s all relative.

"You always have to juxtapose the nominee against the guy who's got the job now. You look at President [Barack] Obama — even Romney is a conservative," Scott said. "And I will say without any question if you look at [Romney’s] record, there’s a couple places where we disagree with him. But fundamentally speaking, his record as governor was a fairly conservative record in many, many ways.

"So if you look at the scope of his work you find yourself saying, 'he’s more conservative than some give him credit,'" Scott said.

Gingrich, the self-proclaimed founder of the so-called Republican revolution and Contract with America, which set out certain conservative principles during the 1994 House of Representatives election, is seen as more ideologically pure.

"I think he can unify the party and get the conservative base of the party fired up," said Dean Allen, one of the founders of South Carolina's Greenville Tea Party.

"My problem with governor Romney: he says a lot of the right things but you don’t get that fire in the belly," said Allen, who said he will probably support Gingrich.

'You always have to juxtapose the nominee against the guy whose got the job now. You look at President [Barack] Obama — even Romney is a conservative.'— Tim Scott, South Carolina Republican congressman

Allen said the conservative base will not get excited about Romney, a perceived moderate, whom they blame for implementing a health insurance policy in Massachusetts that they see as the model for the much-hated "Obamacare." 

Dean scoffed at the conventional wisdom that for Republicans to be more electable, they have to be more moderate, pointing to the recent electoral successes of "true" conservatives in Congress.

"Whether you’re far right or far left, I think independents want somebody who’s a leader, who says 'I know what I’m doing and I can solve the problems,' he said.

"I don’t think we have to moderate our message. I think we have to show strong leadership and eloquently explain why our program is the correct one, and why it will work and that’s how you win people and there’s nobody better at explaining things and debating [than Gingrich]."

As for Romney’s standing among evangelical Christians, Tony Perkins, president of the Family Research Council, a right-wing Christian group, said he has "some work to do."

"The issue here is level of intensity and enthusiasm," Perkins said. "Will they enthusiastically be supporting Mitt Romney? Not at present. He’s going to have to build enthusiasm within that community. He’s avoided their issues, avoided connecting with them."

About 60 per cent of those who voted in the South Carolina primary four years ago identified themselves as evangelical Christians.

And while Romney says he is pro-life and opposes same-sex marriage, many evangelicals remain skeptical about his positions. His Mormon faith seems to be less a factor with that group than what they see as his flip-flops on social issues for political expediency.

While the economy, jobs and international policy are all important issues, Perkins said, a candidate's position on social issues will affect the evangelical vote.

"Evangelical voters — social conservatives — can walk and chew gum at the same time," he said. "If somebody is not pro-life, pro-marriage they’re not going to get the support they need to be successful no matter how good their economic policy is."

'If you can’t beat him in South Carolina, then you can’t beat him anywhere else. '— Dean Allen, Tea Party spokesman, on derailing Mitt Romney

A recent poll suggests more than two thirds of evangelicals in South Carolina don't want Romney as the nominee.

But Gingrich’s history of infidelity — and the latest allegations — mean he won't get a free ride from the Christian right. At a recent gathering in Texas, 114 evangelical leaders voted to endorse Santorum.

In the end, Allen said, it all comes down to South Carolina for those who want to stop Romney's bid for the nomination.

"If you’re going to do it you gotta beat him somewhere," he said. "Coming in second or third or tying doesn't do it. You have to beat him somewhere.

"If you can’t beat him in South Carolina, then you can’t beat him anywhere else. If you can't beat Romney here, you're not going to beat him in Florida and you’re not going to beat him on Super Tuesday."

(Super Tuesday, which falls on March 5, is when the greatest number of states hold primary elections to select delegates to national conventions at which each party's presidential candidates are officially nominated).

"So if Romney wins South Carolina on Saturday, he's the nominee and we’ll live with it," Allen said.