Newt Gingrich, the Republican White House hopeful, was leading in at least four opinion polls, as polling stations opened at 07:00 local time (12:00 GMT) in the US presidential primary in South Carolina.
In surveys taken before voting began, Public Policy Polling said that 35 per cent of registered Republicans in the southern state supported Gingrich, a former congressman and House of Representatives speaker, over the previous front-runner, Mitt Romney, who received 29 per cent of the support.
The two candidates are both trailed by the former Pennsylvania senator, Rick Santorum, and the former congressman, Ron Paul.
Another survey, the Palmetto Poll, showed Gingrich leading in South Carolina with 32 per cent, Romney on 26 per cent and 20 per cent undecided.
Al Jazeera’s Alan Fisher, reporting from Columbia in South Carolina, said people will have 12 hours to vote in the state on Saturday.
"When the polls close at seven o’clock on Saturday night, we should get the first exit polls which will give us an indication on whether or not New Gingrich has actually won here and whether that aura surrounding Mitt Romney has finally been pierced," he said.
"It has been a bad week for Mitt Romney. Just seven days ago people were predicting he would win and win well here in South Carolina, giving him a clean sweep of the first three contests.
"But in the last few days, he has found out after a recount of the vote, he did not win Iowa at all in the first contest.
"And his lead in [South Carolina] has been eaten away by the surge from Newt Gingrich, who seems to have blown past all the problems and all the questions about his personal life."
Stripped of victory
Romney was stripped on Thursday of his victory in the January 3 Iowa caucuses by state party officials, who said a recount showed Santorum ahead by 34 votes.
Romney, a former Massachusetts governor, has struggled in recent days with questions about his personal wealth and taxes, while Gingrich has been surging in polls after a pair of well-received debate performances.
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Gingrich strongly criticised the US media at the presidential debate in South Carolina on Thursday and strenuously denied an allegation that he asked his second wife to tolerate an "open marriage".
"I'm appalled that you would begin a presidential debate on a topic like that," Gingrich said in the CNN-sponsored debate.
The debate got off to an unpredictable start when John King, the moderator, asked Gingrich to respond to charges put forth by his ex-wife Marianne that he had sought an "open marriage" while having an affair.
"I think the disruptive, vicious, negative nature of the news media makes it harder to govern this country," Gingrich said.
He came under attack frequently in the debate of almost two hours and deftly defended himself.
In a move designed to embarrass Romney, Gingrich released his most recent tax returns, a reminder that Romney, a multi-millionaire, still had not produced his own. Romney has pledged to do so in April.
Gingrich is trying to establish himself as the conservative alternative to Romney, who some Republicans see as too moderate.
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Romney has benefited in the sense that Gingrich, Santorum and the Texas governor, Rick Perry, have divided the conservative vote.
However, the contest narrowed on Thursday, with Perry dropping out and throwing his support to Gingrich.
Patrick Driggers, of Charleston, told Al Jazeera he’ll "probably" vote for former Speaker of the House Gingrich. "I like his attitude. Somebody asked him, 'Don’t you feel like you offended some people when you said that they should have jobs and not get food stamps?' He goes, ‘No.’ I like that. … Look ... they’re all cheats, they’re all liars," he said.
"But you’ve just got to find one that’s going to have the right idea, and at least point us somewhat in the right direction. That’s the only thing you can hope for. Somebody that’s not going to screw us."
In Greenville, a town in what is considered the more conservative portion of the state, Al Jazeera's Rob Reynolds reported that voters were placing a premium on social issues.
"The top reason [they are voting for someone] is that they believe that the candidate they were supporting had conservative values in accord with their own," he said, having spoken to voters in the city.
Romney has been helped in South Carolina by the state's governor, Nikki Haley, formerly a favourite of Tea Party conservatives.
"The coolest thing we could ever see is a jobs candidate go up against a government-loving President Obama," she said in Charleston with Romney.
"Get out there and vote," Romney told a crowd of about 200 people.