MOUNT PLEASANT, S.C. - Gov. Christie returned to South Carolina for the first time as an official presidential candidate Monday, laying out a number of conservative positions on gun control and abortion, but asserting he was best suited to break gridlock in Washington because of his experience in working with Democrats in New Jersey.

Speaking at two town-hall-style meetings, in Hilton Head Island in the morning and outside Charleston in the evening, Christie assailed President Obama's accord with Iran over its nuclear program and said Obama's was the worst presidency since Jimmy Carter's.

He also linked the deal with Iran, struck by the United States and five other world powers, to Democratic front-runner Hillary Rodham Clinton.

"She owns the big lie of the second Obama term," Christie said to applause from about 250 people at the Liberty Tap Room in Mount Pleasant. "We are going to feed it to her in November of 2016."

The Republican governor pitched his plan to overhaul Social Security and Medicare, and fielded questions on issues such as Obamacare, Donald Trump, and Planned Parenthood.

Asked if he would defund Planned Parenthood and order his attorney general to investigate the organization, Christie said, "Yes, yes, I would."

Those remarks came after an antiabortion group released a video last week that it said showed a Planned Parenthood executive discussing how the organization sells tissue from aborted fetuses for medical research. Planned Parenthood told Congress on Monday that the secretly recorded video was fraudulent.

Christie noted that he had repeatedly vetoed funding for family-planning centers in New Jersey.

Christie also drew a line on firearms, telling the audience in Hilton Head that authorities should enforce existing laws and punish criminals.

"I don't think we need more gun laws on the books in the United States," he said. "We have plenty."

Christie has vetoed some gun-control legislation in New Jersey, such as a measure that would have limited magazine capacity to 10 bullets from 15. But he also signed anti-gun-violence legislation in 2013, including one bill that required certain mental-health records to be sent to a federal background-check database.

In a sign of how he may try to distinguish himself from a field of more than a dozen candidates seeking the GOP nomination, Christie told the standing-room-only crowd at a restaurant in Hilton Head that it was important to consider not just their policy positions but, "also you need to know who the person is."

Christie described his mother's rules while he was growing up: "You got a problem, say it. You got an issue, tell me. And I'm going to tell you."

Christie repeated the oft-told story of when he visited his mother as she lay dying from lung cancer, and she told him to go back to work.

" 'There is nothing left unsaid between us,' " Christie said his mother told him.

"As probably the most psychoanalyzed politician on the national scene - now, maybe after Mr. Trump, the second-most - people wonder, 'Why do you say the things you say? And why do you say them the way you say them?' " Christie said. "It's her. It's her. That's the way she raised me."

And so Christie told diners in Hilton Head how he felt on a variety of issues. Asked about Trump's controversial remarks, in which he said Arizona Sen. John McCain, a prisoner of war in Vietnam, was not a war hero, Christie responded, to applause: "I am through commenting on things Donald Trump says."

"I know John McCain," Christie said, describing him as an "American hero - period. Stop."

Asked about Obamacare, Christie said he would work to repeal the law and replace it with a decentralized, state-based system.

Christie's visit to South Carolina comes less than a month before the first GOP debate on Aug. 6. He is struggling in the polls, and if he dips further he may not qualify.

In an April Winthrop University poll, 5 percent of likely GOP primary voters said they would vote for Christie if the South Carolina primary were held then. The leading vote-getters were Wisconsin Gov. Scott Walker (13.6 percent) and former Florida Gov. Jeb Bush (12.7 percent).

A more problematic statistic for Christie is 53 percent of respondents said they would not consider voting for him, while just 26 percent said they could support him.

But Christie, a former U.S. attorney, expressed confidence that he would make the debate, telling diners in Mount Pleasant that he would be the "only person on stage who has actually prosecuted terrorists."

"The source of my confidence is that the people behind me aren't going to catch me, and I'll likely move up [in the polls] than move down," he told reporters. "I'll be there. I know that there are some who will hope than I am not, but I'll be there. Don't worry about it."

And he asserted that his executive experience, plus his ability to work with the other party, set him apart from his rivals.

He met with a warm reception Monday. "To me, he came across as humble. I loved when he talked about his mom - very sincere," said Raymond Dohm of North Charleston, a 68-year-old retiree.

Radames Cocco, 37, a contractor from Charleston, said Christie had won his vote. "I like the way he handles the unions," he said.

Christie has devoted most of his campaigning thus far to New Hampshire, which holds the first primary in February. His campaign boasts that Christie has made more stops in New Hampshire this year than any other presidential candidate.

He swung through South Carolina last year in his capacity as chairman of the Republican Governors Association to help raise money for Gov. Nikki Haley's reelection. He held a meet-and-greet last month in Greenville before he officially announced his candidacy.

Christie is next scheduled to head to Iowa on Friday to campaign in the state that holds the first caucus.