Texas Gov. Rick Perry has a narrow lead over former Massachusetts Gov. Mitt Romney among those who plan to vote in South Carolina's Republican presidential primary, according to a new poll.

The Winthrop Poll, released Tuesday, found Perry backed by 30.5 percent of GOP voters, compared with 27.3 percent for Romney.

Winthrop Poll director Scott Huffmon said Perry's support is particularly strong among tea party supporters. "Perry also does about 10 points better among evangelicals, who he's definitely trying to target," Huffmon said.

The next closest candidate was Atlanta resident and former Godfather's Pizza CEO Herman Cain, who had 7.7 percent, followed by former Alaska Gov. Sarah Palin, 5.8 percent but not in the race; former Speaker of the House Newt Gingrich, 5.3 percent; Texas Rep. Ron Paul, 4.2 percent; Minnesota Rep. Michele Bachmann, 3.5 percent; former Utah Gov. Jon Huntsman, 1.6 percent; and former Pennsylvania Sen. Rick Santorum, 1.5 percent.

Eleven percent said they weren't sure. The state's presidential primary, the first in the South, will be held early next year; no date has been set.

The poll's results also underscore Republicans' doubts about President Barack Obama's Christian faith -- 29.5 percent said he is a Muslim.

Five months after the president released his Hawaiian birth certificate, 36 percent of the state's Republicans believe he probably or definitely was born outside the United States.

The poll also found that 69.3 percent of state Republicans approve of Gov. Nikki Haley's performance so far, while 18.2 percent disapprove. Shown the results, Haley said, "Polls are polls. My No. 1 goal is to get people back to work in South Carolina. That's the only poll I care about."

The phone poll was conducted from Sept. 11 to 18 among 1,552 registered South Carolina voters. Most questions were asked only of the 596 voters who said they lean Republican. The margin of error was plus or minus 4 percentage points on those questions.