Texas Governor Rick Perry has dropped out of the race for the Republican US presidential nomination and endorsed former House Speaker Newt Gingrich.
Mr Perry entered the race in August and briefly shot to the front of the pack before gaffes and poor debate performances set him back.
His departure leaves four candidates in the Republican race.
Former Massachusetts Governor Mitt Romney is the front-runner in the state-by-state race for the party's nomination to challenge Democratic President Barack Obama for the White House this November, the BBC reports.
Recent opinion polls have shown a resurgent Mr Gingrich gaining on Mr Romney, although he still trails by about 10 percentage points.
However, in a move which could damage Mr Gingrich, his former wife, Marianne, has made claimed in a TV interview that he asked her to have an open marriage, which she refused.
She claims he conducted an extramarital affair with the woman who would become his third wife, Calista.
The BBC says the interview could hurt Mr Gingrich in South Carolina, where religious and cultural conservatives are a big part of the Republican base.
The final results of the Iowa caucuses were certified as a split decision between Mitt Romney and former Pennsylvania senator Rick Santorum, because of missing data.
Mr Romney had initially been declared the winner of the 3 January nominating contest by eight votes.
But the final count shows Mr Santorum ahead by 34 votes, although no winner has been declared because the results from eight precincts are missing.