A rising star of the Republican Party fell to earth in flames yesterday after he was forced to make a tearful confession of his affair with an Argentine woman.

Mark Sanford’s admission, and the publication of steamy e-mails between the two, could not have been worse for a party that seeks to champion family values and moral rectitude.

During a bizarre six-day disappearance the Governor of South Carolina lied to staff that he had gone hiking along the Appalachian Trail, got caught sneaking back into the country off a flight from Buenos Aires, and then — when he finally reappeared in public — was unable to answer a simple question about whether he was separated from his wife. “I don’t know how you want to define that. She’s there, I’m here,” he replied, adding: “I spent the last five days crying in Argentina.”

Mr Sanford faced questions yesterday about whether he had broken the law by going missing for several days without transferring emergency powers or had used taxpayers’ money on any of his trips to Argentina.

Some South Carolinian politicians were calling on him to resign as chief executive of the state before his second and final term expires. Few doubt that the political career of a man who — until this week — had been mentioned as a likely contender for the 2012 Republican presidential nomination, is over. Mary Matalin, the veteran Republican strategist, said: “You can survive indiscretions; you can’t survive wackiness.”

His humiliation continued as The State, a South Carolina newspaper, published a series of private e-mails that provided more excruciating detail of a love affair that he had described as a “whole sparking thing”. His mistress was identified by Argentine newspapers as María Belén Shapur, 43, a former student at St Catherine’s College, Oxford.

The e-mails show the internal struggles of a religious conservative awkwardly donning the mantle of adulterer as he mixed wholesome descriptions of family life with steamier language about “the erotic beauty of you holding yourself (or two magnificent parts of yourself) in the faded glow of night’s light”.

Mr Sanford, 49, is but the latest in a series of potential Republican leaders who have crashed, burnt or simply left the field in the past months during which the party’s most effective champion has been former Vice-President Dick Cheney, one of the most unpopular politicians in American history.

Sarah Palin, its vice-presidential nominee last year who briefly galvanised John McCain’s campaign, was already mired in doubts about her readiness for high office before being embroiled in a bitter child support row with Levi Johnston, the absentee father of her unmarried daughter’s baby. He is now an aspiring model and actor with an agent who has urged him to adopt the name “Ricky Hollywood”. His mother, Sherry Johnston, has been arrested in Alaska on drug charges.

Bobby Jindal, the young Governor of Louisiana who had been mentioned as an Indian American — and Republican — antidote to Mr Obama, is still struggling to recover from his televised response to the President’s State of the Union speech in February. His performance was so wooden that it has been the butt of jokes ever since.

Jon Huntsman, the Governor of Utah, who might have helped to lead Republicans back to the centre on social issues, has given up the fight by accepting a job offer from Mr Obama to be US Ambassador to China.

Other possible presidential candidates have destroyed their prospects in similar fashion to Mr Sanford. Senator John Ensign had begun to explore the possibility of running in 2012 but was forced last week to admit an affair with a former campaign aide, apparently because her husband was trying to blackmail him. Extramarital or inappropriate sex has become epidemic among many of the Christian conservatives who, like Mr Sanford and Mr Ensign, tried to impeach Bill Clinton for his relationship with Monica Lewinsky in the 1990s.

Senator Larry Craig was caught propositioning a male police officer. David Vitter confessed to “a very serious sin” with prostitutes. Mark Foley quit the House of Representatives in 2006 after making advances towards congressional page boys.

“If Republicans talk about family values, people will roll their eyes,” said Matthew Dowd, a former adviser to George Bush.

Although Democrats, notably the former New York Governor Eliot Spitzer and the presidential candidate John Edwards, have had their troubles, Tony Perkins, president of the Family Research Council, said that Republicans were more vulnerable. As champions of Christian morality, “they are held to a higher standard”.

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