|Perry placed high in initial polling when he entered the race in August but has since lost much support [Reuters]
Rick Perry has withdrawn from the race for the Republican US presidential nomination and endorsed Newt Gingrich as the best man to take on Barack Obama in November's election.
The Texas governor ended his campaign at a news conference on Thursday in North Charleston, South Carolina, where the remaining four candidates are later due to participate in a televised debate prior to Saturday's primary vote.
"I have come to the conclusion that there is no viable path forward for me in this 2012 campaign. Therefore today I am suspending my campaign and endorsing Newt Gingrich for president of the United States," Perry said.
"The journey leads me back to Texas, neither discouraged nor disenchanted.
"We must rise to the occasion and elect a conservative candidate to put this country back on track," he said, referring to Gingrich. "Newt is not perfect, but who among us is?"
Gingrich, the former House speaker, is considered the main conservative rival to frontrunner Mitt Romney. Rick Santorum, a former Pennsylvania senator, and Ron Paul, a Texas congressman, are the remaining two candidates still in the race.
"Perry wants to see a conservative candidate win," said Al Jazeera's Alan Fisher, reporting from Columbia, South Carolina.
"According to [the latest polls], Newt Gingrich is just three points behind Romney in the race in South Carolina. By getting about four or five per cent of Rick Perry's votes, it puts Newt Gingrich in an incredibly strong position."
Perry's endorsement provided a boost for Gingrich on the same day that ABC News aired an interview with a former wife of the presidential hopeful, who said he had asked her to participate in an "open marriage" as he disclosed an affair with a congressional staffer who he is now married to.
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"[He said] 'Callista doesn't care what I do' ... "He was asking to have an open marriage, and I refused... [He asked] that I accept the fact that he has somebody else in his life," Marianne Gingrich said in the interview.
Perry led polls of the Republican candidates after he jumped into the race in August, but committed a series of gaffes on the campaign trail and in debates.
He finished fifth in the Iowa caucuses on January 3, and sixth in the New Hampshire primary on January 10, having chosen not to campaign there in order to focus on South Carolina.
Polls of voters in South Carolina showed that Perry had about five per cent of the vote.
He was rated "even behind a TV comedian who entered the race as a bit of a joke," said our correspondent, referring to Stephen Colbert, host of Comedy Central's Colbert Report, who announced the possibility of running for "Republican president of South Carolina" last week.
Santorum 'wins Iowa'
The battle for the Republican nomination was further complicated on Thursday when certified results released by the Iowa Republican Party revealed that the state's caucuses had been won Rick Santorum, rather than Romney as originally announced, by a margin of 34 votes.
Romney, who went on to win in New Hampshire, had been declared the winner by eight votes on the night of the caucuses.
"Suddenly, all the momentum that was been behind Romney has been sucked out," our correspondent said.
The Iowa caucuses were the first contest in the state-by-state battle to decide who should face Obama on November 6.