MYRTLE BEACH, S.C. — Jon Huntsman will drop out of the Republican presidential campaign Monday and endorse rival Mitt Romney, a campaign source said late Sunday.

The former governor of Utah never caught on with the Republican primary electorate, suspect for accepting President Barack Obama’s nomination to be his ambassador to China, and branded as too moderate for his acceptance of the science of global warming.

He skipped the Iowa caucuses _ too conservative _ and bet it all on New Hampshire only to finish a distant third in that state’s primary last week. Huntsman called his third place finish a “ticket to ride” to South Carolina. But polls show he wasn’t catching on in the state and even the endorsement of South Carolina's most prominent newspaper, The State, wasn’t likely to rejuvenate his prospects.

Polls showed him tied for last place with Gov. Rick Perry of Texas in both South Carolina and Florida, which votes on Jan. 31 and where Huntsman once based his campaign.

His backing of Romney, the former Massachusetts governor, comes five days before the South Carolina primary. A Romney win in the state would be his third straight, and make him appear unstoppable for the nomination.

Though Huntsman has criticized Romney, a fellow Mormon, many said he likely decided to endorse Romney as the party’s best chance to defeat Obama and best prospect to govern the country out of its economic and fiscal mess.

There had been little hint of such a decision earlier in the day, which many of the candidates observed by praying.

Huntsman attended church Sunday in Charleston with former South Carolina Atty. Gen. Henry McMaster, but the attention was on the more conservative candidates who are vying to win the support of South Carolina's born again Christian voters.

Rick Santorum and Rick Perry attended a prayer breakfast in Myrtle Beach, and Newt Gingrich confessed his personal “baggage” at a church in North Charleston. Evangelical voters made up 60 percent of primary voters four years ago. Polls suggest they are split among the candidates. Rallying much of that vote could help one candidate catch Mitt Romney, who leads.

Santorum, in particular, looked for a surge of support thanks to a weekend endorsement from a group of national religious and social conservatives.

“It’s a very big deal,” the former senator from Pennsylvania said on the Fox News Sunday program of the group's move.

“We feel very, very good that with their support were going to get a network of grassroots leaders here, riding up behind us and giving us that surge that we need coming down to this last week.”

Sen. John McCain, who won the 2008 primary, called the backing a setback for Romney, whom he supports. “It is a hit,” McCain said on CNN. “Let's be very honest. There is a very strong evangelical movement in South Carolina, particularly inland.”

Regardless of movement leaders, candidates fanned out to make their appeal directly to voters.

“I know what the values are of South Carolina. I’ve spent a lot of time here,” Santorum told several hundred at a prayer breakfast.

“The question is, will the people of South Carolina vote their conscience,” Santorum said. “Quit compromising. Vote your conscience. …Speak as South Carolinians to a country that is looking for leadership and put someone in there, give someone the opportunity, to do what’s necessary to heal this land.” Perry told the same audience in Myrtle Beach about his faith.

“At age 14, I walked down that (church) aisle and gave my heart to Jesus Christ,” the governor of Texas said. “A few times, I tried to take it back, but God would never leave me alone.”

Perry urged attendees to pick a candidate that embodies their Christian ideals. “Who will be faithful to your values?” he asked.

At the Cathedral of Praise in North Charleston, Gingrich spoke to a congregation of about 1,000 about his three marriages, a record that many voters cite as a reason they won't vote for the former House speaker.

"I don't come here today as a perfect person,” he said. “I don't come here today without, I guess the advertisement is, baggage."

He won admiring words _ though not an endorsement _ from church pastor Michael Lewis.

"Whoever you vote for I think you would have to attest that there's a man who loves his country and who knows his country, and regardless who you vote for, he's one of us," Lewis said in his closing remarks.

Several South Carolina Republicans said it was a sign of how much the state is changing that it had welcomed two Mormons _ Romney and Huntsman _ and two Roman Catholics _ Gingrich and Santorum.

“There’s been such an influx of population into the state…snowbirds that have retired here from the North or have gotten tired of dodging hurricanes in Florida,” said Mike Campbell, son of former Gov. Carroll Campbell, an architect of the state’s first-in-the-South primary.

“These are people who are more independent-leaning and not as far right leaning. You’ll always have a base of social conservatives and evangelicals. But this year it’s more important to all voters to figure out who is going to create a job for them that’s going to put food on the table and who’s going to reform taxes so they can keep more of their own money.”

(David Lightman in Washington and Gina Smith of The State newspaper in Columbia, S.C., contributed to this report.)

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