Charles Kennedy is not the first leader of the Liberal Democrats or its precursor Liberal Party to have awkward personal problems made uncomfortably public. His confession that he has sought “professional help” in a battle with alcohol was as dignified and brave as it must have been difficult. It would be hoped that even in Westminster the hearts of opponents go out to someone who has reluctantly bared a part of his soul. But sympathy for the man is not the same as sympathy for the politician. With regard to his future as Liberal Democrat leader, yesterday’s admission was a red herring.

It is true that Mr Kennedy’s “medical problem” has been inextricably intertwined with his political troubles. It was therefore right that he should step up to the microphone rather than face death by a thousand drink-related rumours. Mr Kennedy is not the first politician to have a drink problem and will not be the last, although only eight months ago he was standing as a potential prime minister. But drink alone is not the issue. If a reformed drinker can become President of the United States, a reformed drinker can lead the Liberal Democrats.

The issue is Mr Kennedy’s leadership. His boast to be the most successful third-party leader for half a century, while numerically accurate, is specious. He should have returned to Westminster last May with many more than 62 MPs, given the favourable backdrop of a fiercely unpopular war which both the other main parties supported. Since then, Mr Kennedy has not so much made false moves as made no moves. The political landscape is changing. David Cameron has called the bluff of the Liberal Democrats’ ambiguity by aiming for the centre ground. Gordon Brown’s ascension to No 10 will alter the mix further. Yet Mr Kennedy has shown little idea how to respond, to the understandable frustration of some of the more talented Liberal Democrat MPs.

Mr Kennedy’s supporters will no doubt try to portray his decision to open up a leadership ballot as a politically brave move deserving of the sympathy vote. His cohorts, like many officials in Westminster, are not shy of tough tactics. But, in reality, his quest comes from a position of weakness. It appears that he can only just command the support of a thin majority of his frontbench spokesmen and women. Even though the Liberal Democrat leader is elected by the whole party, someone who cannot command the support of its MPs will struggle to succeed.

His decision to stand in the forthcoming contest, to replicate the tactics of John Major in 1995, extends an invitation to his critics to stand that should not be ignored. Sir Menzies Campbell would have been a serious contender for the job and his decision not to stand is a setback for a party now seemingly unable to run even a leadership contest. At least one of the promising MPs from the Orange Book group should stand, if for no other reason than to force the party to define its political character. This is not a moment for timidity, politeness or undue deference (or cowardice).

When Mr Major dropped his bombshell, all his critics, notably Michael Portillo, were cowed into silence apart from the somewhat eccentric John Redwood. Mr Major’s victory was a setback for his party, which was buried by a new Labour landslide within two years. The Liberal Democrats must have a serious, defining contest.