Nick Clegg is plainly right:

it is wholly unacceptable for a senior Liberal Democrat to commission private polls questioning the party's leadership in the week of a vital election.

The resignation of Lord Oakeshott, the member concerned, was inevitable after his identity was exposed. But this is politics, where rights and wrongs do not always matter as much as perception, and the perception from the outside is that the party is on the brink, at risk of tearing itself apart.

Mr Clegg insists he is the man to lead the party into next year's General Election and still has the backing of the vast majority of members. But leadership is about confidence and, when that leaches away, it is perilously hard to regain confidence.

Strong interventions from other senior party figures such as Lord Ashdown and Charles Kennedy urging calm have not entirely stilled the panic in LibDem breasts.

This is not really surprising after the party suffered a catastrophic loss of support in the European and English local elections. Party activists, already fearful, will approach next year's General Election with something approaching dread.

But what did the party's leaders expect? Mr Clegg used to argue for a realignment of the centre-left, as did many Liberal leaders before him. He used to describe progressive conservatism as a myth.

It is no wonder that so many liberal-minded supporters are so dismayed by the role the party has played since 2010. It has backed policies that are diametrically opposed to their views and those of many who voted LibDem.

Yet Mr Clegg and his fellow LibDem ministers seem not to have had a strategy for offsetting the electoral cost of coalition government.

The hard choices the party has made are being proved right, Mr Clegg argues, as he urges supporters to hold their nerve. However, if austerity is working, it is still only really evident in some parts of the UK and, if it succeeds, it will be Chancellor George Osborne who banks most of the credit.

Voters who previously only had principles by which to judge the LibDems now have experience of the party in government and their verdict is harsh. Lord Oakeshott suggests his party has become a "split-the-difference centre party with no roots, no principles and no values'. Many grassroots members feel his analysis is correct, even if his intervention has been less than helpful.

A leadership contest this side of a the General Election would not help. Far from averting a LibDem collapse at Westminster, it would probably hasten it. Also, any serious candidates are tarnished by ministerial service in the present administration.

Mr Clegg remains the man to lead the party. But reasserting its values, and persuading the public to trust it may already be beyond him. Certainly, his task has been made all the more difficult.