The conservative bedrock issues of abortion, gay marriage and faith that have long shaped Republican campaigns in the South moved toward the forefront of the presidential contest here Saturday as candidates scrambled for the support of evangelical voters.

Rick Santorum got a potential boost Saturday as a coalition of prominent Christian conservative leaders voted to back his candidacy in a last-ditch effort to consolidate social conservative voters and stop, or at least slow, Mitt Romney’s march to the GOP nomination.

But it was unclear whether the decision of about 150 conservatives meeting in Texas would change the contours of the race in South Carolina. This state’s powerful evangelical vote appears scattered, and Santorum is battling with four other candidates to overtake Romney, who leads in the polls heading into the potentially decisive primary Saturday.

Santorum, the former Pennsylvania senator who nearly beat Romney in the Iowa caucuses, stepped up his critique of the front-runner by saying his shifting positions on social issues in particular render him insufficiently conservative to be the Republican Party’s standard-bearer.

“The establishment is trying to ram down the people of South Carolina’s and everybody else’s throat Governor Romney, as if he is inevitable,” Santorum told about 200 people at Tommy’s Country Ham House in Greenville, S.C., according to CNN.

After spending the week mostly beating back attacks on his work as founder and chief executive of the venture capital and corporate buyout firm Bain Capital, Romney on Saturday tried to double down on his opposition to abortion rights. The former Massachusetts governor, who supported abortion rights earlier in his political career, released a new Web video, “Shares Our Values,” featuring a testimonial from supporter Mary Ann Glendon, a former ambassador and founder of Women Affirming Life.

“The pro-life movement is all about changing hearts and minds,” she said.

Romney, campaigning here in Sumter with South Carolina Gov. Nikki Haley (R) and NASCAR legend Bobby Allison, highlighted his belief in the country’s religious roots. “We’re not a secular nation,” he said. “We’re a nation that believes in a provident hand.”

But Romney spoke mostly about President Obama, sharpening his critique of Obama’s economic stewardship.

“He likes to say that he has had extensive experience working alongside hardworking Americans,” Romney told several hundred supporters here. “I think it helps to have actually been a hardworking American in a hardworking American job. . . . He will have to do a lot of explaining about how it is that being a community organizer taught him how to fix the economy.”

The other GOP candidates are trying to put Romney’s evolving social positions under the microscope here. For generations, Southern Baptists have shaped South Carolina politics; in the 2008 race, more than half of Republican primary voters identified themselves as born-again Christians.

But this time, two Mormons — Romney and former Utah governor Jon Huntsman Jr. — and two Catholics — Santorum and former House speaker Newt Gingrich — are among the six major candidates vying for the nomination.

Their courtship of Christian voters has pushed some of them into less comfortable environments. Huntsman and his wife, Mary Kaye, announced plans to attend an Episcopal church service in Charleston on Sunday. Romney, at a Friday event, was asked whether he believes in “the divine saving grace of Jesus Christ.” He said he did.

Newt Gingrich held a town hall meeting at Jones Memorial AME Zion Church, a black church in Columbia, where about 50 people gathered to hear the speaker. Over about an hour, he fielded questions on comments he made about about blacks and welfare, and his characterization of Obama as a “food stamp president.” He didn’t back down from that statement, yet the visit allowed him to make good on his pledge to take his message to “ethnic communities.”

Meanwhile, Santorum hoped the Texas vote by evangelical leaders would help build momentum. But in a sign the move might have come too late, the leaders did not discuss any plans to urge Gingrich or Texas Gov. Rick Perry to drop out of the race, nor did they lay plans to mobilize voters on Santorum’s behalf, according to participants.

All the major candidates except Huntsman sent representatives to the meeting. After what was described as a passionate discussion and three rounds of balloting, Santorum won the support of more than two-thirds of the leaders present, according to Family Research Council President Tony Perkins.

Although Perkins said the meeting was not designed to “bash Mitt Romney,” he and other conservative leaders are alarmed at the prospect of Romney as the Republican nominee. They are trying to rally behind a single alternative to avoid the outcome of the 2008 race, when the evangelical vote split and Sen. John McCain (Ariz.) won with a plurality on his way to securing the nomination.

Staff writers Nia-Malika Henderson in Columbia and Felicia Sonmez in Washington contributed to this report.