Updated: 3 polls show Gingrich leading SC race after debate

Three new polls released Thursday and Friday have Newt Gingrich leading in South Carolina over Mitt Romney, while a fourth poll showed the former House Speaker received a boost from his debate performance Monday.

Gingrich leads Romney by 35 percent to 29 percent, according to a poll released Friday by Public Policy Polling. Gingrich has risen from 23 percent over the last two weeks as other candidates faltered.

Rasmussen has Gingrich at 33 percent versus Romney’s 31 percent in a poll released Thursday. Romney held a 14-point lead in a Rasmussen poll taken just before Monday’s debate.

American Research Group puts Gingrich with 33 percent, narrowly ahead of Romney at 32 percent in a poll released Thursday.

In a poll released Thursday by NBC/Marist, Romney has 34 percent over Gingrich's 24 percent. But the poll was taken before and after the debate in Myrtle Beach.

Before the debate, Romney led Gingrich by 37 percent to 22 percent. After Romney fumbled on several questions including one about his taxes and Gingrich won a standing ovation for how he would get the poor back to work, Romney's post-debate lead over Gingrich shrank 31 percent to 26 percent.

S.C. voters cast ballots on Saturday.

In addition to his strong showing at Monday’s debate, Gingrich received a push from Sarah Palin, who said she would vote for him in the South Carolina primary. Palin’s husband, Todd, formally threw his support behind Gingrich.

While some voters have expressed displeasure over Romney's role with the Bain Capital investment firm and opinions that he is more moderate than other candidates, Gingrich is facing a challenge with "Nightline" planning to air an interview with his second wife later tonight. Marianne Gingrich said her ex-husband wanted an open marriage.

All three polls had Texas congressman Ron Paul in third at 15 to 19 percent. Former U.S. Sen. Rick Santorum finished fourth in all three polls at nine to 14 percent. Santorum’s results in Rasmussen polling are down five points since Monday and 13 points since winning the Iowa primary.

Nearly one-third of likely S.C. primary voters said they could change their minds, Rasmussen said. evangelical Christians and Tea Party voters all favored Gingrich heavily in the Public Policy Polling, American Research Group and Rasmussen polls.

Still, 62 percent of all S.C. voters think Romney will win the GOP presidential nomination, down from 69 percent two days ago, Rasmussen found. Polling numbers and margins of error: Rasmussen - 750 likely S.C. primary voters, plus or minus 4 percent; Public Policy Polling - 836 likely S.C. primary voters, plus or minus 3.4 percent. American Research Group - 600 likely voters, plus or minus 4 percent; NBC News/Marist - 684 likely S.C. primary voters, plus or minus 3.8 percent.