Republican presidential candidate Lindsey Graham is dropping out of the 2016 race for the White House.

The South Carolina senator is the fourth GOP contender to drop out of the race, following Texas Gov. Rick Perry, Wisconsin Gov. Scott Walker and Louisiana Gov. Bobby Jindal. The move leaves 13 candidates remaining in the race for the Republican nod.

"I must suspend my campaign," he said on CNN this morning. "I'm not going to suspend my desire to help the country. I'll probably go back to Iraq and Afghanistan and get another update. Thirty-six trips has informed me. But the one thing I feel really good about is I did it with a smile on my face. I talked about things that are important to me and somebody better fix one day."

Later, in a phone interview with ABC News, Graham said, "I'm just going to chill out today," adding he hasn't decided whom to endorse yet. "There's lots of talented people in the race: Marco Rubio, Jeb Bush, others."

Graham, 60, had been included in the undercard debates during his campaign, struggling to garner any significant support in national or early state polls. "I’m far more confident today that our party will reject the Obama doctrine of leading from behind and will provide the strong leadership America needs," Graham says in a campaign video.

The South Carolina Republican Party removed Graham’s name from the ballot there, a letter from the state GOP confirms to ABC News. Today marks the deadline to have any candidate's name removed from the South Carolina ballot.

“This letter shall certify the removal of Lindsey Graham’s name from South Carolina’s February 20, 2016 Republican Presidential Preference Primary ballot,” South Carolina GOP chair Matt Moore wrote to the state’s election commission.

The move potentially spares Graham from a poor performance in his home state.

"I have offered a detailed plan to win a war we cannot afford to lose and to turn back the tide of isolationism that has been rising in the Republican Party," Graham, whose campaign for the presidency lasted 204 days, said in a recent statement. "I believe we made enormous progress in this effort."

"Senator Graham has an incredibly strong and loyal grassroots network in South Carolina," GOP state chair Matt Moore said. "Given Senator Graham's huge [Senate] primary victory in South Carolina just last year, the Graham network could have a major impact on South Carolina's presidential primary."

But Democrats pointed to Graham's support of comprehensive immigration reform. "The one presidential candidate who has consistently favored comprehensive immigration reform just dropped out of the race after attracting virtually no support," Democratic National Committee spokesman Eric Walker said in a statement.

In a statement, Graham's close friend Arizona Sen. John McCain expressed his gratitude for Graham's bid. "It is a pity that a bifurcated debate structure kept his voice and views from the wider public that needed to hear them," he said. "With Senator Lindsey Graham’s announcement, Republicans lost our most qualified, thoughtful, fearless and honest presidential candidate, not to mention the candidate with the best (and it seemed sometimes the only) sense of humor."

Other candidates expressed their thanks to Graham on Twitter for running in the race.

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