(David Goldman/AP Photo)

ABC News' Michael Falcone reports:

Jon Huntsman will drop out of the Republican presidential race  on Monday, a campaign spokesman told ABC News.

A source close to the Huntsman campaign said the former ambassador to China and Utah governor was "proud of the race that he ran" but "did not want to stand in the way" of rival Mitt Romney, the current front-runner for the Republican nomination.

Huntsman plans to endorse Romney at an 11 a.m. press conference Monday in Myrtle Beach, S.C.

After a disappointing third place finish in New Hampshire - a contest on which he had staked his candidacy - Huntsman vowed to fight on. In his concession speech in New Hampshire, he told his supporters:  "I say third place is a ticket to ride, ladies and gentleman! Hello, South Carolina!"

But just six days from the South Carolina primary, Huntsman has said goodbye to the Palmetto state after all.

A source close to the Huntsman campaign said that Romney is "not currently" planning to attend Huntsman's Monday morning drop-out/endorsement announcement by the former Utah governor in South Carolina.

A Huntsman aide tells ABC News that the decision came in the wake of the results of the New Hampshire primary.

"He has been discussing with his family after they woke up after a successful evening in New Hampshire. They felt good about their performance in New Hampshire, but he and his family had a discussion and this is the decision they came to," the aide said. "At the end of the day he decided he did not want to hurt the best chance of beating Barack Obama and that's Mitt Romney. By continuing into South Carolina and Florida, that's what he would have been doing."

Word of Huntsman's decision comes the same day that the biggest newspaper in South Carolina endorsed him.

The State newspaper of Columbia touted Huntsman's resume, pointing to his record as governor of Utah, and his service as ambassador to both Bush and Obama.

"Mr. Huntsman is a true conservative, with a record and platform of bold economic reform straight out of the free-market bible, but he's a realist, whose goal is likewise to get things done," the paper wrote. "Under his leadership, Utah led the nation in job creation, and the Pew Center on the States ranked it the best-managed state in the nation."

After attending church this morning with his wife Mary Kaye and daughter Gracie Mei, Huntsman said he was happy to have the endorsement.

"I think it's a big deal anytime you get the largest paper in the state to come out and endorse you that's a big deal," he said. "I thought it was well written and well argued."

In an interview with ABC News, South Carolina Republican Party Chairman Chad Connelly praised Huntsman for running a "spirited campaign" but acknowledged that his exit from the field "doesn't change the dynamics of the race" in the Palmetto State.

While Huntsman will be throwing his support to Romney on Monday, it was only a week ago that he told ABC's John Berman just the opposite.

When asked if he trusts Governor Romney, Huntsman replied, "He has not put forth reason to give us a reason for us to trust him."

Earlier this month, he told another ABC reporter that Romney is "completely out of touch."

Huntsman's campaign had actually started several websites attacking Romney over the course of the campaign. Those sites - www.scaredmittless2012.com, for instance - no redirect to other sites like yahoo.com.

"We've removed lots of things from the website as most campaigns do when they are over," a Huntsman campaign explained to ABC.

As recently as Saturday, Huntsman was questioning Romney's electability.

Reporters asked Huntsman if any of the Republican establishment  had reached out to him and asked him to tone down his criticism of Romney and his work with Bain Capital. Huntsman explained: "Nope. And listen. I have said what I have said. My problem is really a political issue. And that is, when you have a candidate that talks about enjoyment in firing people, talks about pink-slips, who makes a comment that seem to be so detached from the problems that Americans are facing today, that makes you pretty much unelectable. And I say, we want a nominee who can actually go on to win. That's the issue … the bigger issue is one of electability."

Huntsman, 51, entered the race last summer to high expectations, but he struggled from the start to win over conservative Republican voters.

Huntsman is now the fourth Republican candidate to drop out of the campaign. Tim Pawlenty, the former governor Minnesota, dropped out last summer after a disappointing finish in the Iowa straw poll. Rep. Michele Bachmann of Minnesota dropped out just after the Iowa Caucus and businessman Herman Cain left the race in a storm of sexual harassment allegations.

With Huntsman's endorsement of Romney on Monday as well as Pawlenty's endorsement of Romney last summer, two of the four have thrown their support behind the former Massachusetts governor. The other two - Cain and Bachmann - have yet to endorse.

 ABC's John Berman, Jonathan Karl,  Shushannah Walshe, Elicia Dover, Susan Archer and Sara Just contributed to this report.