A new political party may emerge as disgruntled Labour moderates team up with the Liberal Democrats following Jeremy Corbyn's election win, former Cabinet minister Sir Vince Cable has suggested.
The senior Lib Dem made the prediction as he called for a "common sense centre-left formation" to oppose the Conservatives.
The former business secretary said there were "millions of people" who wanted an alternative to the Tories but would not back Labour under Mr Corbyn and shadow chancellor John McDonnell.
Sir Vince's comments came after Lib Dem leader Tim Farron claimed his party offers the only credible alternative to a generation of Tory rule despite the Lib Dems' disastrous general election result.
Writing in the Mail on Sunday, Sir Vince forecast that some Labour supporters - and possibly MPs - would switch to the Lib Dems because of their concern about the left-wing nature of Mr Corbyn's politics.
In the long run Sir Vince, a veteran of the 1980s split which saw the SDP break away from Labour, predicted that an entire new centre-left party could emerge.
He said: "There are many voters who will never back the Tories, and are now desperately unhappy with Labour's leftward lurch, who will be looking for a new home.
"I think we may get some people coming across. It may even become an avalanche, although I doubt it. Defection is never an easy option, as I know all too well.
"I am a veteran of the party's civil war in the early 1980s, albeit as a foot soldier rather than a general. Those of us who like me jumped ship to the SDP had mixed success. The Tories remained in power for over a decade.
"But the influence of the SDP on ideas and policies was immense.
"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."
As the Lib Dem conference in Bournemouth began, Mr Farron pinned his hopes for a Lib Dem revival on offering a new home to disaffected Labour members and voters distressed at the election of Mr Corbyn.
The Lib Dems were left reeling in May as their 56 MPs were reduced to a rump of eight, triggering Nick Clegg's resignation as leader following five years in government.
In his first conference appearance as leader, Mr Farron attempted to rally the party's activists, insisting that the surge in membership since the election - with more than 20,000 people signing up - was the sign of a fightback.
Mr Farron, who condemned the "fantasy economics" offered by Mr Corbyn and Mr McDonnell, said: "We once again see the prospect of a decade or more of Tory rule, and it fills us with dread."
He told activists: "If Labour aren't interested in standing up to the Tories and providing a credible opposition, that's their funeral.
"The Liberal Democrats will fill that space. Radical and liberal and responsible too."
At the conference's opening rally in Bournemouth, Mr Farron said: "When the tectonic plates of politics move, they sometimes move immensely quickly - that is what is happening now.
"These are momentous and historic times, history calls us, we will answer that call.
"Britain needs a party that is progressive, moderate and liberal. We are that party. This is our moment."