Some senior party members are worried that Mr Ashdown's surprise announcement will create six months of turmoil and distract the party from the May elections to local authorities, the Scottish and Welsh assemblies and the European Parliament poll, which will be Mr Ashdown's swansong.
The Liberal Democrats are urgently drawing up a code of conduct for candidates in the hope of avoiding a damaging display of disunity which could reduce their election prospects.
Baroness Maddock, the party president, who will oversee the election, will urge MPs not to criticise each other or appear together on television and radio programmes, so they cannot be portrayed as rivals.
Potential candidates will be told not to declare their intention to run "formally or informally" until Mr Ashdown has stood down. "We cannot afford the distraction of electioneering for the leadership while the campaign for this year's crucial elections is in progress," said Lady Maddock.
But it was clear yesterday it will be difficult for the Liberal Democrats to hold the line, as "friends" of the candidates eagerly talked up their chances so as not to be stuck in the starting blocks in June.
Some were critical of Mr Ashdown for leaving a six-month vacuum. "I don't understand why he could not have announced his decision as soon as the Euro elections were over," said one potential leadership candidate. "We don't need a six-month campaign."
It emerged yesterday that Mr Ashdown's successor may not be elected by the party's 90,000 members until September. Officials believe there may not be enough time to run a contest between the Euro poll in June and the August summer break. The new leader would then have a "coronation" at the party's annual conference at Harrogate in September.
The Liberal Democrat spring conference, in Edinburgh in March, will inevitably become a "beauty contest" for the candidates. "The important thing is that they don't overtly fight each other, which would damage the party," said one party source.
Only two weeks ago, Mr Ashdown's aides dismissed speculation that he might be forced to resign this year by saying he believed there was no capable candidate ready to take over."We are not exactly blessed with a galaxy of stars," one insider admitted last night.
This could strengthen the claims of Menzies Campbell, at 58 the oldest of the potential runners, who might well offer his services as the man to take the party through the next general election, allowing younger pretenders to win more spurs.
One MP said the "smart money" was on Mr Campbell because he would appeal to MPs elected in 1997 who might also be reluctant to back a younger man.
Mr Campbell, the party's foreign affairs spokesman, was doing nothing to discourage speculation that he would run yesterday. Although close to Mr Ashdown, he said that, while the Liberal Democrats would continue to co-operate with the Government where they agreed, they opposed it for not spending enough on health and education. Nick Harvey, the campaigns chief who is seen as Mr Ashdown's favoured successor, said the agreement with Labour would survive but not in exactly the same way because "the personal chemistry is obviously a considerable part of it".
Simon Hughes, the only contender who voted against Mr Ashdown's decision to forge closer links with Mr Blair last November, admitted he had "fallen out" with his leader over the policy.
William Hill Ladbrokes
Charles Kennedy evens 4-5
Nick Harvey 7-2 4-1
Simon Hughes 4-1 5-2
Menzies Campbell 3-1 7-1
Malcolm Bruce 20-1 14-1
Matthew Taylor 20-1 12-1
Alan Beith 33-1 20-1
Paul Tyler 33-1 20-1Reuse content