Jon M. Huntsman Jr. informed his advisers on Sunday that he intends to drop out of the Republican presidential race, ending his candidacy a week before he had hoped to revive his campaign in the South Carolina primary.
Mr. Huntsman, who had struggled to live up to the soaring expectations of his candidacy, made plans to make an announcement as early as Monday. He had been set to participate in an evening debate in Myrtle Beach.
A third-place finish in the New Hampshire primary last week failed to jump start his flagging candidacy, aides said, and his campaign limped into South Carolina with little money. Mr. Huntsman has spent days pondering his future in the race, but aides said that he concluded he was unlikely to topple Mitt Romney or match the momentum of his Republican rivals in the conservative Southern primary.