Fred Thompson, the former Tennessee senator, has dropped out of the US Republican presidential race.
"I hope that my country and my party have benefited from our having made this effort," Thompson said in a statement released by his campaign on Tuesday.
Thompson had finished in third place in South Carolina's Republican primary on Saturday having already performed badly in the New Hampshire and Iowa races.
He did not say in his statement whether or not he would endorse one of his former rivals.
Thompson, an actor who had mulled a presidential bid since March last year, had held second place in national polls in October, after touting his strong conservative credentials.
However his popularity plummeted after apathetic performances during campaigning and a perception by some voters that he did not want the presidency enough.
Some political pundits had argued that Thompson drew support away from Mike Huckabee - the former Arkansas governor - in South Carolina, which in turn helped John McCain, the Arizona senator, to victory there.
Huckabee told the US MSNBC television channel he felt he could have won South Carolina "if there had been a margin and Fred had not been there."