Hillary Clinton carefully evaded questions last night about the prostitution scandal engulfing her political ally Eliot Spitzer, the Governor of New York.

Speaking at a campaign stop in Pennsylvania, after Mr Spitzer apologised for paying for sex with a high-priced prostitute, the New York senator sent her best wishes but said that it was too early to add anything else on the accusations.

“I don’t have any comment on that. Obviously I am sending my best wishes and thoughts to the governor and to his family,” Mrs Clinton said as she began campaigning in the state ahead of its April 22 primary.

Mr Spitzer is one of Mrs Clinton's superdelegates, the elected officials and party leaders who are set to play a crucial role in determining the presidential nominee if the Democratic primaries end in deadlock.

If Mr Spitzer resigns, he would not be replaced as a superdelegate, meaning Mrs Clinton would lose one, according to the Democratic National Committee.

David Paterson, the Lieutenant Governor of New York, would become governor, and he already is a superdelegate supporting Mrs Clinton.

Swiftly moving to sever all links, it took the presidential candidate less than one hour from the story breaking to remove all mention of Mr Spitzer's endorsement last May from her campaign website, the online magazine Radar reported.

Mr Spitzer issued a humble public apology on Monday after he was accused of paying for sex as a client of the high-class prostitution ring Emperors Club VIP. The authorities said that he was caught on a federal wiretap arranging a tryst with a call girl at a Washington hotel room on the night of February 13.

The governor, who was once tipped as a possible future president, reportedly admitted to senior aides that he was a client of the international escort service, which charged up to $5,500 (£2,750) an hour.

Spanning London, Paris, New York, Los Angeles and Miami, the ring ranked prostitutes with a number of diamonds, while payments could be made by credit card. Court papers suggested unusual, perhaps risky, sexual practices.

“I have acted in a way that violates my obligations to my family and in a way that violates my or any sense of right and wrong,” Mr Spitzer said last night, with his wife Silda standing by his side. “I apologise first and most importantly to my family. I apologise to the public, whom I have promised better. I am disappointed I have not lived up to the standards I have set for myself.”

Mrs Clinton would not be drawn on whether Mr Spitzer could survive the scandal, which has triggered calls for his resignation. “Let’s wait and see what comes out of the next few days,” she said. “Right now I don’t have any comment. I think it’s appropriate to wish his family well and see how things develop.”

While the Democratic presidential candidate is not personally close to Mr Spitzer, the pair have been on friendly professional terms since Mrs Clinton first ran for the Senate in 2000. Her aides said that Mrs Clinton deeply respected Mr Spitzer’s work during eight years as New York’s Attorney General, where his crusade against corporate corruption and investment excesses earned him a reputation as “the sheriff of Wall Street.”

His difficulties will undermine her efforts to paint her rival Barack Obama as morally dubious due to his links with Tony Rekzo, a former political patron on trial in Chicago for alleged fraud and corruption.

Neither can she take a strong moral stand against Mr Spitzer, who is married with three daughters, due to her own husband's legendary philandering while occupying the Oval Office.

However this is not the first political headache that Mr Spitzer has unintentionally caused Mrs Clinton. Questioned in a televised debate last autumn about his proposal to provide illegal immigrants with drivers’ licenses, she appeared to vacillate between support and opposition, prompting a flurry of criticism and negative ads.

She later said she opposed the plan but had not wanted to damage Mr Spitzer by saying so.

A handful of Mrs Clinton’s high-profile supporters have already been forced to apologise for sexual misbehavior. Early in 2007, San Francisco Mayor Gavin Newsom publicly apologised for having a relationship with the wife of a top political aide. He blamed alcohol dependence for his actions and checked into rehab. Shortly after endorsing Mrs Clinton in May 2007, Los Angeles Mayor Antonio Villaraigosa, a rising Hispanic star in the Democratic Party, announced he was divorcing his wife after conducting affair with a local television news anchor for several months.

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