WASHINGTON -- Republican Sen. Lindsey Graham ended his 2016 campaign for president Monday, saying he remains committed to working to achieve security for the American people.

Having mustered little support in the polls, Graham's exit will not have an immediate effect on the race in the final stretch before the Feb. 1 Iowa caucuses and the Feb. 9 New Hampshire primary. But his decision could produce a ripple effect in his home state of South Carolina, which follows New Hampshire with a Feb. 20 primary. Some leading Republicans in South Carolina have remained uncommitted to this point out of loyalty to their senior senator, but now are free to take sides. Graham, too, could make an endorsement, though he's given no indication of when that might be.

Graham, 60, plunged into the contest in June on a platform of hawkish foreign policy and a declaration that newcomers need not apply for a job that offers no chance for "on-the-job training." At the time, anything was possible because none in the crowded field of Republican candidates was capturing a sizable base of support.

But over the summer, political neophytes Donald Trump and Ben Carson surged to the front of the pack and forced far better-known candidates, such as former Florida Gov. Jeb Bush, to fight for support.

Graham, urged to run by 2008 Republican presidential nominee John McCain, won so little backing in national polls that he failed to qualify even for the second tier Republican debate in November.

An Air Force veteran and reservist, Graham is a foreign-policy hawk who has called President Barack Obama "a small-minded guy in big times." After the attacks on Paris that killed 129 people, Graham pushed for an authorization of military force against the Islamic State that would allow the U.S. to attack the groups' supporters anywhere, with no time limit.

Virtually every Republican candidate has blasted Obama as weak on foreign policy, but Graham was often the only would-be nominee who did not hedge when asked about whether he would deploy more ground troops. He stated from the outset of his campaign that more U.S. troops are needed, adding that "American soldiers will die in Iraq and eventually in Syria to protect our homeland."

Barrow reported from Atlanta.