Norman Baker called for a vote of confidence on Charles Kennedy only hours before the Liberal Democrat leader admitted his drinking problem to the nation.

The Lewes MP's intervention is a blow to Mr Kennedy as it comes from a loyal member of his Shadow Cabinet.

There has been widespread doubt about the impact drink was having on his performance as party leader, resulting in fervent speculation about a leadership challenge.

Mr Kennedy finally confessed to receiving treatment for a drink problem at a news conference last night.

He said: "I've called this press conference to address one issue directly and one that's been a source of concern for me and others for some time.

"Over the past 18 months I've been coming to terms and seeking to cope with a drinking problem, and I've come to learn that a drink problem is a serious problem indeed.

"It's serious for yourself and it's serious for those around you. I've sought professional help and I believe today this issue is essentially resolved."

The Lib Dem leader has stood defiant amid weeks of criticism from his own MPs that he has lost momentum since the General Election and lacks the energy and commitment to the job.

Most of the sniping had been briefed anonymously but this week, a series of high-profile figures demanded a leadership vote.

Mr Baker yesterday told The Argus the enduring questions over Mr Kennedy's authority had to be put to bed, one way or another.

He said: "I didn't know he was going to make this announcement but it didn't entirely surprise me because it was always a possibility.

"We now have an opportunity to see if the party members want a leadership contest. It is also an opportunity for us to take the media spotlight and get some of our ideas across.

"I think his speech was very brave; it is a difficult thing to do in front of anyone, never mind 60 million people.

"My objective was always to bring the matter to a head and now that has happened."

Mr Baker, one the party's most senior MPs and Shadow Environment Secretary, has ruled himself out of any subsequent leadership election. But he called on Mr Kennedy to bring the situation to a head next week, when MPs return to Westminster following the Christmas break.

Mr Kennedy insisted yesterday he retained the confidence of both MPs and party members and appealed to his critics to wait until after the May local elections to settle the issue.

But Mr Baker's call was backed by other senior MPs. Susan Kramer said Mr Kennedy had "lost control".

Baroness Tonge said: "I think it's now gone too far.

"Next week, it's up to the parliamentary party to do something about it."