COLUMBIA, S.C.-What do you get when evangelical leaders like Gary Bauer, James Dobson, Donald Wildmon, and other social conservatives huddle at a Texas retreat during the middle of the GOP presidential primary season? According to Bauer, there's one thing you won't get: "A stop-Romney meeting."

But if Saturday's meeting of nearly 150 evangelical leaders and social conservatives in Bernham, Texas, wasn't an effort to stop the former Massachusetts governor, it did become something else: an endorsement of Rick Santorum.

A week after Bauer endorsed former Sen. Rick Santorum of Pennsylvania for the GOP nomination, evangelicals leaders at the meeting he helped organized did the same, throwing their support behind the socially conservative Catholic.

If any candidate, including Santorum, hopes to overtake current GOP frontrunner Mitt Romney in the South Carolina primary this coming Saturday, the moment is critical. Winning the widespread support of social conservatives could boost second-tier candidates in a race that's getting harder to win after Romney's victories in Iowa and New Hampshire.

By Monday, Real Clear Politics (RCP) reported Romney holding a nearly 8-point lead in the South Carolina race, though a Reuters poll put his lead at nearly 20 points. The Reuters poll also reported Santorum and Rep. Ron Paul of Texas tied for second place, while RCP had former House Speaker Newt Gingrich in second place. Whatever the pecking order, Romney's opponents are scrambling to gain enough conservative votes to catch the frontrunner they call a moderate.

Meanwhile, Romney could pick up some of Jon Huntsman's supporters in South Carolina. The former Utah governor, who polls showed was accounting for 5 percent of the South Carolina vote, withdrew from the race on Monday and endorsed Romney. (See "Huntsman out," by Edward Lee Pitts.)

Last Wednesday at a rally in Rock Hill, S.C.-just one day after placing fourth in the New Hampshire primary-Gingrich drew a stark line for South Carolina voters: "You're either going to center in and pick one conservative, or by default give a moderate the nomination."

It's unclear whether Santorum's fresh support from national evangelical leaders will help him gain ground on Romney in South Carolina. It's also unclear how hard Romney will fight for evangelical votes. With a comfortable lead and $19 million of campaign cash in hand (after raising $24 million in the last three months of 2011), the frontrunner may stick to his economic message while other candidates take on issues like abortion, marriage, and religious liberty.

If Romney does win the nomination, Bauer says he'll support him and encourage other evangelicals to do the same. He shares the sentiment that unites many across South Carolina, even if they support different GOP candidates: The one person they're determined to stop is President Barack Obama.

If Gingrich is a second-tier candidate, his events don't feel like second-tier affairs. Some 300 people battled rain and thick fog to pack a Rock Hill country club for last Wednesday's Gingrich rally at 9 a.m. on a weekday. As crowds filled a standing-room-only section near a huge American flag, a campaign staffer announced that Gingrich would arrive soon and stay late: "He'll stay here until he meets every single one of you."

That's part of a strategy that Gingrich adopted after his campaign nearly imploded last year. Staffers complained that the candidate didn't campaign enough. Now he typically speaks for 30 minutes, takes questions for 30 minutes, and then shakes hands until the last person leaves.

In a state where six-out-of-10 GOP voters identify as born-again Christians or evangelicals, Gingrich hit the right buttons: Before mentioning the economy, the former Georgia congressman talked about the challenge of "anti-Christian religious bigotry." He noted that Catholic Charities in Massachusetts ended its adoption services because it refused to follow a state law requiring the agency to help same-sex couples adopt. "We will not tolerate a speech dictatorship in this country," he said to cheers, and also insisted America should speak out for the religious liberty of persecuted Christians in places like Iraq, Egypt, and Nigeria.

A series of questions from the audience showed that economic issues were the dominant concern. Gingrich easily rattled off data about South Carolina manufacturing woes but said less about his brutal attacks on Romney's work as portfolio manager at Bain Capital. Gingrich had slammed Romney's work at the firm that included closing some companies, but the criticism backfired: Other GOP candidates, including Santorum and Rep. Ron Paul, defended Romney's work as part of free enterprise.

The most glaring target of the morning remained Obama and his policies, and the biggest applause line of the day came when Gingrich vowed to undo the president's healthcare legislation. But concerns about Gingrich's character and temperament aren't going away, so he prefers to talk about the importance of South Carolina's primary: "I believe the next 10 days [before the primary] are as important to American history as any other we've seen in American modern politics."

Romney set the stakes high, too: In his first appearance in South Carolina after winning the New Hampshire primary, the former governor last Wednesday told a crowd of about 300 people in Columbia that the presidential race was about preserving the soul of America. That mostly centered on controlling spiraling debt, managing the economy, and protecting national security-issues over which voters consistently express deep concern.

When it comes to social issues, Romney isn't as aggressive: Though he regularly answers debate questions by saying that he's pro-life and against same-sex marriage, he doesn't include those issues in stump speeches.

Mark DeMoss-an evangelical and an unpaid adviser to the Romney campaign-said the candidate hasn't focused on evangelical outreach during this primary season: "Gov. Romney has an outreach to America." (Curtis Loftis-the South Carolina state treasurer and chairman of Romney's campaign in the Palmetto State-says he's met with social conservatives to promote the candidate.)

For Romney volunteer Vicki Robbins, social issues are important, but economic woes dominate. As she distributed Romney stickers outside his campaign event, Robbins said she weighed all the candidates but liked Romney's business record and economic proposals. Most of all, she said she likes Romney for one central reason: "We need to beat Obama, and I believe he's the one who can do it."

That may be Romney's trump card. Polls show many Republican voters placing a high priority on nominating a candidate who can win the general election. And Romney's win in New Hampshire-a far less conservative state than South Carolina-suggests he could appeal to a broader base. The candidate gained voters across categories, including evangelicals: Romney took 31 percent of self-identified evangelicals, while Santorum won 23 percent. (Santorum easily won evangelical voters in Iowa.) Romney also took 33 percent of the independent vote, while second-place finisher Ron Paul took 30 percent.

But despite perceived electability, some undecided voters still have concerns. The formerly pro-abortion Romney emphasizes that he's now pro-life, but he still faces doubts from some voters. At the Gingrich rally earlier in the day, Lou Pantuosco said while he's most concerned about a candidate who could improve the country's manufacturing sector, he's also concerned about social issues like abortion and marriage. When it comes to Romney, the undecided voter feels unsure: "I guess that's what he believes. I just don't think he'd fight for it."

That may be Santorum's trump card. The former senator from Pennsylvania boasts a staunchly pro-life voting record and an unambiguous opposition to same-sex marriage. Though he doesn't lead with those issues, voters often ask him about them. The candidate faced a barrage of questions about gay marriage during his New Hampshire campaign and often endured jeers from crowds when he expressed opposition.

When a caller to a radio show told Santorum that the race didn't need "a Jesus candidate," the outspoken Catholic said he wouldn't mind being called that name: "We always need a Jesus candidate. I don't mean necessarily that we always need a Christian, but we need someone who believes in something more than themselves."

That theme ran through the candidate's speech during a rally just after Romney's event in Columbia. Santorum spoke mostly about the economy but also discussed American rights and where they come from: "They come from a loving God who gave us rights because we are made in His image." He later answered a question about abortion and same-sex marriage by saying, "All the other candidates have similar positions, but I'm told I'm the extremist candidate. Maybe it's because I'm the only one who talks about it. And maybe it seems like I mean it."

Santorum connects well with voters on emotional issues like pro-life concerns. He regularly tries to explain connections between economic and social issues, and to bring in historical perspective. That led to some of his answers to questions at the rally last Wednesday running long, with some audience members looking at their watches. For example, Santorum's answer to a question about balanced budgets led to a book recommendation about George Washington and a discussion of the British Empire.

When it comes to being competitive with Romney, Santorum supporter Bobby Scott thinks that his appeal to evangelicals will help: "If his message clicks with people, I think that's going to make the difference." But Santorum's critics charge that he voted for big government spending during his time as a senator, and they question whether his economic plans will bring about needed changes. The candidate counters that if his plans are more modest than the plans of his opponents, they are also more doable.