IT was the kind of ringing endorsement that any politician would normally be proud to hear. Senator David Vitter of Louisiana was “one of the nicest and most honourable men I’ve ever met”, a constituent declared last week.

The only problem for Vitter – and for many of his Republican party colleagues – was that the constituent was Jeanette Maier, a former New Orleans brothel madam who claimed the right-wing senator used to be one of her favourite customers.

They have dubbed him Sinator Vitter, a former holier-than-thou conservative braggart whose frequent lectures about the sanctity of marriage have made him a target for derision after revelations about his alleged enthusiasm for the company of prostitutes in both New Orleans and Washington.

As if they did not already have enough on their plates trying to distance themselves from President George W Bush’s policies in Iraq, Vitter’s fellow Republicans on Capitol Hill are quaking at the prospect of a new purge of so-called “moral hypocrites” who preach Christian virtue before nipping off for an extra-marital quickie.

Vitter’s brush with sexual scandal continues a Louisiana tradition of politicians caught with their trousers down. But it has also come at an awkward moment for an increasingly ragged Republican party that for much of the past decade has relied on high moral principle as its safest election vote-winner.

Vitter, a 46-year-old father of four, is expected to return to Capitol Hill this week after missing key Senate votes while he reportedly begged God and his family for forgiveness. His colleagues hope the begging worked because Vitter’s wife, Wendy, once hinted publicly she would cut off his penis if she caught him with another woman.

Although by Louisiana standards Vitter’s sinning was modest – one state governor famously remarked that he would only lose an election if he were “caught in bed with a dead girl or a live boy” – a public backlash against years of right-wing

Republican sermonising has transformed one man’s fall from grace into a potential turning point in America’s debate over abortion, gay marriage and so-called family values.

The man behind Vitter’s fall was Larry Flynt, the veteran pornographer and publisher of Hustler magazine. Outraged by Republican treatment of former president Bill Clinton during the Monica Lewinsky scandal, Flynt has become the scourge of Washington politicians with sexual secrets. He has hired investigators and offered rewards of up to $1m for damning details.

When it emerged earlier this year that Deborah Palfrey, the owner of a Washington escort service, was threatening to publish the telephone numbers of her clients, Flynt went to work. His investigators established that Vitter’s numbers appeared on the list provided by the so-called “DC Madam”.

Flynt claimed that his investigation provoked last Monday’s statement by Vitter apologising for what the senator called “a very serious sin in my past”. Vitter said he wanted to “keep discussion of the matter . . . with God and [my family]”, but any hope he had that the issue might swiftly blow over dissolved when Maier came forward.

The New Orleans madam insisted she was trying to help out her former customer, but every word she uttered made Republicans squirm. “He’s a good man,” she said. “He was not a freak. He was not into anything unusual or kinky or weird. We were looking at the man, not his penis.”

With Vitter understandably in hiding, it was left to his spokesman to denounce the media for reporting “rumours and false accusations”. But Flynt was in high spirits. “This is payback time,” he said. “I’m not exposing anyone’s sex life . . . I’m exposing the hypocrisy. I don’t want men like that legislating for me, especially in areas of morality.”

Flynt also warned he was on the trail of other senators and congressmen – the numbers shifted between 20 and 30 in interviews. He said a recent full-page advertisement he placed in The Washington Post had yielded promising tips. “If I get just a couple of those phonies out of there, maybe it will be a step forward,” he said.

Support for Vitter was muted last week, and even some of his Republican colleagues acknowledged it might be difficult for him to keep his job after everything he had said about the importance of marriage. During the Lewinsky affair, Vitter described Clinton as “morally unfit to govern”. He even led a campaign in the Senate for a programme encouraging youths to practise sexual abstinence.

Vitter was also a supporter of Rudy Giuliani, the former New York mayor who had hoped that an alliance with the southern senator might ease his own problems with America’s religious conservatives. Giuliani was earlier embarrassed when his South Carolina campaign manager was indicted on cocaine charges.

Conservative morale was further dented last week when a married Florida state congressman who had campaigned for “family values” was charged with offering oral sex to a male undercover cop. One of Vitter’s senatorial colleagues hinted that more scandal may lie ahead.

“All of us have to look at it and say that we could be next,” said Senator Jim DeMint of South Carolina. “We all think that we’re not vulnerable . . . but the fact is Washington can be a very lonely and isolating place.”

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