Tim Farron has declared he has entered the Liberal Democrat leadership race.
The former party president told BBC Radio 4's Today programme:
Mr Farron joins former health minister Norman Lamb as the contenders to replace Nick Clegg following the party's disastrous general election results.
Tim Farron, one of the Liberal Democrats' last remaining MPs, has insisted that his party is not dead despite their dreadful showing in Thursday's General Election.
He told ITV News that if his party did not exist, "you would have to invent it".
He said: "We are absolutely going to fight back and rebuild from the grass roots, because the space is there that needs to be filled."
President of the Liberal Democrats Tim Farron says Britain needs his party because the Conservatives are the "nasty party...trying to balance the books on the backs of the poor" and Labour are "an incompetent rabble that got us into this mess in the first place".
Speaking on the Sky News Murnaghan programme Mr Farron said Britain needs the Lib Dems to "balance the economy with compassion for people".
Mr Farron also insisted the mood at the party's conference is "forward-looking" despite a YouGov poll in the Sunday Times showing the party could lose MPs in the next General Election.
He said: "We shouldn't be fixated on polls. The polls show, if nothing else, that there is everything to play for."
Mr Farron added that the coalition government had worked together but "agreed to differ" on certain issues and as the election approaches some of the differences will become more obvious.
Liberal Democrat president Tim Farron has appealed for an end to "absolutely foolish" calls for Nick Clegg to quit as party leader.
In a call for unity Mr Farron said: "Nick Clegg should undoubtedly stay and the Liberal Democrats should stay the course in Government."
He told The Andrew Marr Show: "I have lost elections before and it is miserable, and I also understand why these people will feel that the message that they got back on the doorstep, that they don't like us being in government and so on, is a really difficult one.
"But I just think, at this time, it would be absolutely foolish for us as a party to turn on ourselves."
The Liberal Democrats wants to see the so-called 'bedroom tax' changed so that people do not face moving out of their home with nowhere to go, the party's president has told ITV News.
Current policy means social housing tenants who have a spare room face having their housing benefit reduced.
Speaking to Deputy Political Editor Chris Ship, Tim Farron said Nick Clegg shared "the view that this is something that we want to see changed".
Lib Dem president Tim Farron said he thinks leader Nick Clegg has acted "totally appropriately" regarding the claims make against Lord Rennard.
Mr Farron told Sky News: "We are a democratic party ... we must follow the due processes.
"The lesson we must learn ... is that you do not let things fester - there is nothing kind about putting a complaint to one side".
He added, "If we can't learn from this process it will be an appalling waste".
The Liberal Democrat party president Tim Farron has told ITV News Deputy Political Editor Chris Ship that the Home Office 'listened to us' over not proceeding with rolling out controversial 'go home' vans nationwide:
The Liberal Democrats have criticised their Conservative coalition partners for being inconsistent and warned their flagship housing policy could do more harm than good.
Speaking at the party's conference in Glasgow, Liberal Democrat party president Tim Farron said:
Liberal Democrat president Tim Farron told ITV News it was "daft" to suggest that companies have a "social duty" to employ young British workers rather than better-qualified immigrants.
Earlier Conservative Business Minister Matthew Hancock said firms have a responsibility to ensure young people in the communities where they are based are given the opportunity to get a job and get on in life.
Mr Farron added: "If the Tories really believe that they wouldn't have employed the Australian Lynton Crosby to run their election campaign."