Republican South Carolina Sen. Lindsey Graham is dropping out of the presidential race.
"While we have run a campaign that has made a real difference, I have concluded this is not my time," he said in a statement Monday.
"I am suspending my campaign but never my commitment to achieving security through strength for the American people," he said.
Graham, who first told CNN of his decision in an interview, faced a deadline Monday to be removed from the GOP primary ballot in his home state of South Carolina. Graham has been mired at the bottom of polls - both nationally and in his home state - and could have faced an embarrassing showing in the state's February primary.
In the CNN interview, Graham said it was "the joy of my life" to run for president. He did not disclose which Republican candidate he plans to endorse but noted that Marco Rubio and Jeb Bush "get it" when it comes to foreign policy.
A supporter of comprehensive immigration reform and an aggressive interventionist foreign policy, Graham never gained traction as a presidential candidate despite his extensive national security experience and the quick wit he displayed on the campaign trail.
The hawkish South Carolina senator had been the Republican field's most vociferous early critic of Donald Trump.
In last week's Republican debate, Graham - who was relegated to an earlier "undercard" contest - apologized to the Muslim world for Trump's rhetoric about Islam.
"To all of our Muslim friends throughout the world, like the King of Jordan and the President of Egypt, I am sorry. He does not represent us," Graham said.
The South Carolina senator warred with Trump from the early days of the campaign, when Trump gave out Graham's cell phone number at a public event. Graham responded with a parody video depicting him destroying his telephone with fire, a microwave and a golf club.
Former GOP presidential nominee and top Graham ally Sen. John McCain said in a statement that "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."
And several of the senator's fellow 2016 competitors praised Graham's leadership on foreign policy issues.