In an emotional statement at the party’s headquarters Mr Kennedy asked party managers to trigger an immediate leadership election to end speculation about his future.

In a challenge to his rebel MPs he declared: “It’s open, of course, to any colleague who believes they can better represent the longer-term interests of the party to stand against me in such a leadership election.”

Last night two of the most serious contenders for the job appeared to rule out standing against him. Sir Menzies Campbell, the deputy leader and favourite to replace Mr Kennedy, announced that he would not stand, while Mark Oaten, the home affairs spokesman, who last month said he would stand if there was an election, also ruled himself out.

The Times learnt last night that a delegation of senior MPs is considering a personal plea for Mr Kennedy to resign of his own accord to spare the party a damaging leadership election in the run-up to the local election campaign in May. One MP said: “It is unimaginable that he will stand. He is in no fit state.”

Another senior unnamed Liberal Democrat was quoted as saying: “The man has gone bonkers.”

Norman Lamb, the party’s trade and industry spokesman, said last night on the BBC’s Newsnight that Mr Kennedy’s confession had made things “very difficult”, adding: “In a sense it’s compromised us all.”

Simon Hughes, the party president, who has grassroots support, said he had not made up his mind what to do. “I have never wanted a leadership election. We need to concentrate on supporting Charles.”

Mr Kennedy was forced to act after suffering two serious blows to his authority. His office was alerted yesterday that a letter of no confidence from half the members of his front bench had been leaked.

Later his office received a call from a journalist preparing to reveal details of his treatment for alcoholism, which Mr Kennedy has always denied. He decided to make a live televised personal statement.

“Over the past 18 months I’ve been coming to terms with and seeking to cope with a drinking problem,” he said. “I have sought professional help and I believe today that this issue is essentially resolved. People close to me know that this has been a struggle and that for extended periods I’ve consumed no alcohol at all.

“As a matter of fact I’ve not had a drink for the past two months and I don’t intend to in the future.”

He added: “So let me be clear: I consider myself to be capable and in good health and remain politically determined as the leader of this party.”

Mr Kennedy then challenged his critics to put up or shut up by telling the party’s managers to put the machinery in place for an immediate leadership election among its 73,000 members.

It was in March 2004 that Mr Kennedy confessed to four of his most senior aides, in his private office in the Commons, that he was seeking treatment for a drink problem. He had been summoned to the meeting after he missed the Budget statement.

Those trusted with the secret included Sir Menzies. The others present were Matthew Taylor, then the party chairman, Lord Rennard, the party’s campaign director, and Andrew Stunnell, the Lib Dem Chief Whip. They were prepared to give him the benefit of the doubt so long as he received professional help. But they became exasperated by his continuing lapses.

The feeling among many MPs was that despite his protestations he had yet to prove that he had beaten the bottle. There was also anger that he had repeatedly denied to his MPs that he had a problem with alcohol.

One senior source said: “He is destroying the party.” Another said that Mr Kennedy’s private office is “beset by a series of crises because of his behaviour”.

There was an immediate show of support among some MPs last night. Lembit Opik, the party’s Wales and Northern Ireland spokesman, urged his 11 fellow frontbenchers who signed the letter to reward Mr Kennedy for admitting his drink problem by withdrawing the letter. “I think the nation will credit him for his courage and I hope the party will support him in his bid to continue as leader,” Mr Opik said.

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