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.
