A spokesman for Mr Ashdown rejected as "absolute nonsense" a report that he was planning to stand down from the party's leadership if Labour won a convincing victory at the general election.
One of his lieutenants, Menzies Campbell, described the report in the Sunday Telegraph as the first sign of the summer "silly season" which followed the recess of Parliament. "Paddy Ashdown will lead the Liberal Democrats for as long as he wants," he said on BBC1's Breakfast with Frost programme.
Rumblings of discontent among MPs about his leadership were reported in the Independent earlier this month. There is no threat of a challenge, but Mr Ashdown, 54, is the oldest of the leaders and is said by his colleagues to be "desperate" to lift his party's standing in the opinion polls.
This Thursday's poll in Littleborough and Saddleworth is crucial to his leadership strategy, but his party's chances of holding on to their lead were not helped by the Tory campaign manager, Nigel Evans.
Mr Evans, a Tory MP, confirmed an opinion poll in the Independent on Saturday showing that Labour had cut the Liberal Democrats' lead.
"The Labour Party certainly is doing better than anyone anticipated," said Mr Evans.
"We have seen on the streets a lot of former Liberal Democrats switching to the Labour Party."
Mr Evans' remarks added fuel to Labour's late charge for the seat amid recriminations between Labour and the Liberal Democrats over "dirty" campaigns.
Mr Campbell accused Peter Mandelson, the MP running Labour's day-to-day by-election campaign, of "deliberate misrepresentation" over the support by Chris Davies, the Liberal Democrat candidate, for liberalising the laws against the use of cannabis.
Mr Mandelson was unabashed. He said: "We have been the underdogs in the campaign and we have fought very hard indeed. The challenge to the Liberal Democrats has considerably rattled them."
Mr Campbell condemned Labour's campaign as "tabloid politics - no different in principle from the kind of thing Neil Kinnock suffered at the hands of the tabloid press."
And he added: "A number of Labour voters have complained ... It is a long way from the kind of new politics we were promised when Mr Blair became leader of the Labour Party."
The Liberal Democrats have counter-attacked, accusing Labour's candidate, Phil Woolas, of nursing left-wing tendencies for once advising students to use firebombs and for lying about living in the constituency.
Mr Evans, from the safety of the Tory camp, said Labour had plunged their campaign into the gutter and that the Liberal Democrats had followed them into it.
"It is the dirtiest campaign I have seen these two parties wage," he said.