The plot that sank Kennedy

Lib Dem leader quits amid threats of more damaging revelations by senior MPs. Damning charge sheet compiled about heavy drinking, absences and behaviour. Leadership contest gets under way as Sir Menzies Campbell says: 'I will stand'

Charles Kennedy resigned yesterday as Liberal Democrat leader after it became clear he would face an onslaught from his most senior MPs, and further revelations about his drinking problem, if he pressed ahead with his plans to fight in a leadership election.

Bowing to overwhelming pressure, Mr Kennedy said it was his "duty" to stand down "in the interests of our party".

His sudden exit after six years as leader came as MPs prepared to reveal the details of further damaging revelations about his performance as leader.

A "charge sheet" of the more embarrassing incidents, including accounts of how he failed to turn up at party meetings and was often bleary-eyed and showing signs of drink- related illness, was being prepared.

MPs spent recent days "comparing notes" about his performance, including drink-related incidents, for use if Mr Kennedy refused to quit.

Mr Kennedy also faced further revelations over his failure to perform or even turn up at key Commons or election events. At the same time his support among the grassroots was ebbing away. Local party leaders and allies contacted the former leader's office yesterday morning calling for him to go, delivering the fatal final blows.

Sir Menzies Campbell, who took over as leader and who has the backing of most senior Lib Dem MPs, immediately announced his intention to stand. A YouGov poll yesterday showed he had 49 per cent support.

Other front-runners - Simon Hughes, the party president, who has widespread grassroots support, and Mark Oaten, the home affairs spokesman - have so far delayed entering the race. Mr Kennedy said he was "standing down as leader with immediate effect".

"I have been in politics for far too long to be overly sentimental about this sort of moment," he said, offering his heartfelt thanks to his wife Sarah and to his closest allies. The former leader sent a thinly coded message that he did not want to see a coronation of Sir Menzies Campbell, his deputy leader.

"Many, many of them have made the point to me that we fought for and founded this party on the fundamental principle of one member, one vote," he said.

"I urge them to stick with us and to exercise that right in the leadership election which now follows. In all of this, the interests of the party have to come first. That is where my personal, political and constitutional duty lies.

"Accordingly, I am announcing today that when nominations open for the leadership of the party I shall not now be putting my name forward." The abrupt resignation announcement, made at 3pm at his party's Westminster headquarters, followed an interview published in The Independent that morning in which he announced that he was determined to fight on.

But close aides of Mr Kennedy said he came to the conclusion that his position was untenable on Friday night after his most senior MPs made it clear he no longer carried their confidence. He was warned that he would lose a confidence vote being planned for this week and could face a damaging leadership contest.

MPs begged him to bow out with dignity and take credit for a term of office which has brought the Liberal Democrats its best election result since 1923.

As tributes to Mr Kennedy from his MPs rolled in, parliamentary colleagues spoke of their relief that he had stood down before a blood-letting occurred.

"He was facing death by 1,000 cuts," said one senior MP.

Chris Davies, Leader of the Liberal Democrat euro-MPs, spoke for many senior party figures when he expressed gratitude that the party had been spared further trauma.

"This was a sad but necessary announcement. The alternative, weeks and months of party division, was unthinkable," he said. "Charles has put the party first and now we can look forward instead of inward."

Senior MPs who have been urging him to go for months warned him privately that he could be badly damaged if he stood for re-election in a leadership contest.

Some of his most senior MPs had complained they had been covering up his illness for years. Sandra Gidley, the party's family spokesman, revealed that she had received a personal assurance that he had dealt with his drink problem as long ago as 2003.

Close allies of Mr Kennedy said his departure was regrettable but the right choice.

Lord Rennard, Chief Executive, of the Liberal Democrats said his departure was "sad but inevitable." The Leader of the Liberal Democrats in the House of Lords, the Right Honourable Lord (Tom) McNally, said: "Charles Kennedy has once again demonstrated enormous courage and dignity.

"He has demonstrated these attributes throughout his leadership - and most crucially when he voiced the concerns of millions about the war in Iraq. He also led our party to two outstanding election advances: a good record on which to depart, and a contribution to public life of which to be proud."

Today manoeuvring among the leadership contenders began immediately, with some MPs calling for the "coronation" of Sir Menzies Campbell.

But others insisted on the full two-month ballot of 70,000 members.

Sir Menzies Campbell, the front-runner, is understood to already have the seven nominations from MPs necessary to stand, and has the overwhelming backing of the parliamentary party.

Simon Hughes, the party President, has widespread support among members of the party, but it is feared that he does not have the backing of many members of Parliament.

But Norman Baker, the Liberal Democrat environment spokesman, said the party should seek to avoid a damaging civil war, and choose Sir Menzies Campbell as its new leader.