The Liberal Democrats have been given the strongest warning yet that they could go "down hill" at the next election.

Frontbencher Simon Hughes, who competed with Charles Kennedy for the leadership, predicted the party would lose around six of the parliamentary seats it has taken from the Tories.

He told party members they had to "work like fury" to ensure they did not start sliding back into irrelevance.

And he controversially urged the new leader to take his party to the "centre left" of the political spectrum.

Speaking to BBC News Online, Mr Hughes said there was a real danger that Mr Kennedy's joke remark when he was elected - "From here on it's down hill all the way" - could come true.

He also suggested Mr Kennedy did not hold strong views on policy and would have to clarify his position in some key areas.

"There is a danger we go down hill simply because the political arithmetic of Britain means that we have got 46 seats - some we won for the first time from the Tories others are held from the Tories - and it will be highly unlikely that the Tories would not recover a bit, even if not very much.

"But a bit would be enough to lose us some of those seats.

'Work like fury'

"So if we are not going to go down hill we are going to have to work like fury to maintain as many of the 46 as possible and, I think we probably can retain most of them - ball park figures, 40 - and then we have to find another six plus so we are going up hill in terms of making progress. I think we can do it but we are not ready yet.

"Literally from this week on it's down to earth and it's down to work because we have at least only a year, maybe two and a half.

"But unless we really organise ourselves effectively, however well we may feel we are doing, we will look as if we are slipping back."

Mr Hughes' words were the clearest expression yet of an underlying message that is coming from the party's leadership.

Charles Kennedy: Has warned against complacency

Mr Kennedy has already warned party activists that they could face some losses at the election.

And he knows he is entering a vital time for the Lib Dems and has to take the hugely difficult decision about where to position the party to maximise its potential support.

If he goes to the left of Labour he risks losing the Tory protest votes and if he goes to the right he will alienate large numbers of his own party members.

He has insisted the party must be "progressive and radical, but not left" - but Mr Hughes said it was exactly the centre left ground being vacated by Labour that the party should target.

Seize the moment

"We have got to get the policy clearer and if we seize our moment then there are opportunities that await us.

"Labour are following the Tories to the right and they are now in the centre. There are places which I would have thought were traditional centre left positions - social justice, redistribution of wealth, tax system issues, environmental issues, civil liberties issues - where we can probably gain votes, the progressive votes that Labour would expect to hold on to," he said.

"It's a difficult balance. Centre left is not the best phrase, but it's the easiest understood analysis."

Mr Hughes, who is widely expected to become Mr Kennedy's deputy, also claimed the new leader's style would be significantly different from Mr Ashdown's.

"Charles is naturally a more relaxed and laid back individual. When Paddy was around there was always a sort of tension a sort of edge a sort of urgency - keeping control, a hands on approach.

"It may be one of the reasons they voted for him not me. They may have thought 'we have had 11 years of being marched up and down and around furiously and we would rather have a leader with slightly less fixed views, definite positions and categoric intentions and we would rather have somebody who listens, takes it all in and then distils it.'

"He has never been a great policy promoter, he has never been an ardent position taker. He has been a member of the team.

"He is a natural liberal, he is comfortable in the party, he is highly competent strategically and therefore people haven't seen the same definitive leadership as they did with Paddy.

"Paddy stuck his head out went out front and everybody knew where he was going.

"With Charles that isn't as clear and he will have to answer some of the questions, but he wants to do it collectively and, to be honest, that is slightly more pleasurable for the rest of us than somebody who told you where you were going next."