Tim Farron has dismissed suggestions that a new centre-left party could be formed to bring together Liberal Democrats and Labour MPs concerned about Jeremy Corbyn's politics.
The Lib Dem leader rejected the suggestion by former Cabinet minister Sir Vince Cable that a new "fully fledged political party" may emerge.
Mr Farron believes that his party would be able to take advantage of a "vast space" in the centre ground caused by Labour's election of left-winger Mr Corbyn and David Cameron's policies since taking office without the restraints imposed on him by the Lib Dems.
As the Lib Dem conference continued in Bournemouth, Mr Farron insisted he wanted to "reach out" to supporters and members of other parties rather than form a new group.
He told BBC1's Andrew Marr Show: "We have got the Liberal Democrats. Why would we create a new party?
"My sense is that there are liberals in other parties who are not yet Liberal Democrats. There are people in the Labour Party, actually there are many people in the Conservatives who think that David Cameron and George Osborne attacking low income workers is a terrible thing to do and think that risking Britain's relevance and prosperity by pulling us out of the European Union or taking that risk is a terrible thing to do.
"I want to reach out to those people."
Despite a disastrous general election, which saw the party's presence in the Commons cut from 56 MPs to just eight, Mr Farron asserted that a combination of being "socially just and economically credible" - unlike the "fantasy economics" offered by Labour - meant they could provide the only credible opposition to the Tories.
Pointing to increased membership and council by-election success since the drubbing in May which saw the Lib Dems ejected from office and ended Nick Clegg's leadership, Mr Farron said: "Don't assume that our position now is the position we must remain. There is a vast space in British politics for a party that is socially just and economically credible. We are determined to fill that space.
"The Tories must not be allowed to get away with the things they are doing without being credibly opposed."
Writing in the Mail on Sunday, Sir Vince, a veteran of the 1980s split which saw the SDP break away from Labour, made his prediction that an entirely new centre-left party could be formed.
He said: "What I hope emerges from this is the creation of a common sense centre-left formation made of sensible Labour, the Lib Dems and indeed some Tories who don't like the direction of their party.
"It will be a very long process but ultimately, this movement might well have to become a fully fledged political party."