Nick Clegg accused right-wing Conservatives of lying over the environment yesterday, as he insisted that the Liberal Democrats had a clear identity distinct from David Cameron's party and could win more seats at the next election.
The Deputy Prime Minister's extraordinary assault on what he called "enemies of progress" was echoed by Vince Cable, who accused some on the Tory right of waging an "ideological jihad" by calling for further cuts on tax and spending.
Mr Clegg will attempt to use his party's victory in Eastleigh to bolster his leadership by telling Lib Dems in Brighton today that they need to harness their appetite for power, using the winning zeal in Eastleigh to scoop more support in 2015. Far from being subsumed by the Tories in coalition, the Liberal Democrat identity is easier to see, he will say, because they are standing side by side.
In his main speech to his party's spring conference, he will say: "The Lib Dems are not a party of protest; we are a party of change. Get back out there. Tell our side of the story. And we will win again."
But with the seaside gathering overshadowed by the Lord Rennard sexual harassment allegations and two members of the party elite, Chris Huhne and Vicky Pryce, facing jail, activists on the fringes of the conference began discussing how long Mr Clegg should remain leader, with support mounting for the party president, Tim Farron.
The Deputy Prime Minister was criticised by some activists for his response to the Rennard affair, who pointed out that he had not yet apologised on behalf of the party.
Speaking yesterday at the launch of a new Lib Dem collection of essays on the environment, entitled The Green Book, Mr Clegg said tensions between his party and the Tories over the environment were "very real". He added: "I am unabashed in saying that we Liberal Democrats have a crucial role to keep this government anchored in the centre ground, not to make it lurch one way or the other, nor allow it to be captured by vested interests or a particular set of prejudices.
"I have probably spent more time with Ed [Davey], and before that with Chris [Huhne], making sure the coalition government does what it said it would do – and, frankly, what the Conservatives said they would do – putting the environment at the heart of our policy-making.
"The centre of gravity on the right of British politics at the moment is to denigrate the importance of the environment, to conduct a systematic, misleading and mendacious campaign which some seem to suggest – or seek to suggest – that somehow protecting the environment is inimical to keeping people's livelihood protected and putting money back into their progress.
"The enemies of progress, enemies of green growth, the enemies of protecting the environment are trying to distort and warp the environmental cause into one which they will claim costs people money and jobs. Nothing could be further from the truth. One thing I can assure you is Ed and I will never, ever bow to that prejudice."
At a fringe meeting of the left-wing Social Liberal Forum, Mr Cable, the Business Secretary, fuelled the cabinet row over departmental cuts and rounded on the Tory "jihad" against state spending.
"What we have to make absolutely clear is that there is a difference between managing public spending, controlling public spending in that context – having that financial discipline – and the kind of thing that a lot of right-wing Conservatives are wishing for, which is a kind of British Tea Party, a kind of ideological jihad against public spending and public services."
He stood by his comments in a New Statesman article last week suggesting that the Government should borrow more to spend on infrastructure to boost growth.
Mr Cable insisted the markets had not "collapsed" as a result of his essay, adding: "The point I was trying to make is that we need to be open-minded and recognise that the balance of these risks may well be changing."
Mr Cable said he was on the "same page" as the Prime Minister, "but we have different emphases and we use different language".
Warning that it would be "utterly counterproductive" to cut his science and skills budgets any further, the Business Secretary added: "Lib Dems in government will not allow that to happen."
Mr Clegg's aides said the leader's speech today was "forward-looking" and would not cover the Lord Rennard affair. Following Eastleigh, the Lib Dems are confident they can "pinch" seats from the Tories in 2015, said aides.
Mr Clegg will say: "There is a myth that governing together, in coalition, diminishes the ability of the smaller party to beat the bigger party – the idea that, in Tory-facing seats, the Liberal Democrats will find it impossible to distinguish our record, our values, from theirs. But that myth has been utterly confounded. The opposite is true. The longer you stand side by side with your opponents, the easier your differences are to see."
Continuing his theme, Mr Clegg will add: "You can't trust Labour to build a strong economy. You can't trust the Tories to build a fair society. Only the Liberal Democrats can deliver a strong economy and a fairer society, enabling everyone to get on."
Nick Clegg heaped praise on Chris Huhne yesterday for his "powerful and effective" work on the environment. The glowing tribute came as it emerged, however, that Huhne was thrown out of the Lib Dems after he pleaded guilty for covering up a speeding offence. In a move showing that the Lib Dem leadership is trying to purge the party of scandal, it was revealed that Huhne was asked to resign his membership while his partner, Carina Trimingham, is also no longer a member. Vicky Pryce, who is awaiting sentencing, is expected to be thrown out of the party.
Lord Rennard could be forced to resign his membership if a party inquiry finds evidence behind allegations of sexual harassment.
At the launch of The Green Book, a collection of essays by Lib Dem environmentalists, Mr Clegg said: "Whatever else has happened with Chris and Vicky … it is worth being reminded that he was an outstanding constituency MP; he was also an extremely powerful thinker and, indeed, very effective secretary of state … on the green agenda."