In an interview with CNN, Graham said, "I'm going to suspend my campaign. I'm not going to suspend my desire to help the country."
Graham, a close friend of 2008 GOP nominee John McCain, is one of the most prominent foreign policy hawks in the Senate. He has used his platform as a candidate to advocate for a more muscular U.S. military presence in the Middle East, frequently citing his dozens of trips to the region.
"The centerpiece of my campaign has been securing our nation. 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 told supporters in an email on Monday.
Graham has also been one of the toughest critics of Donald Trump in the Republican presidential field.
Given his low poll numbers, Graham never had the opportunity to face Trump in a debate. Never making the main stage in any of the Republican debates, Graham has appeared in the undercard matches — except for the fourth debate in November when he failed to make either stage.
Today is the deadline for a candidate to withdraw from the South Carolina primary and get their name removed from the ballot. Graham was potentially facing an embarrassing loss in his home state and now has the leverage of endorsing one of his fellow GOP candidates.