The Labour Party could fracture as badly as it did in 1981 if the party suffers a heavy loss at the next election, Lord Ashdown warned today.
As a bruising week for Gordon Brown draws to a close, the former Liberal Democrat leader told the Daily Telegraph that Labour faces a "heart and soul battle" if it loses power and faces an SDP-style break away.
In 1981 Labour MPs opposed to Michael Foot's leadership - led by the "Gang of Four" which included David Owen and Roy Jenkins - defected from Labour to set up the SDP.
Lord Ashdown told the paper: "What happens if Labour loses? Very senior people have told me there will be a heart and soul battle.
"If there is a real fight, the ingredients will be ripe for a repeat of what happened prior to 1983.
"There are signs that certain constituency parties are growing really Left-wing, such as in Leeds. Senior Labour figures have said to me 'if that happens, I'm off'."
The Telegraph said there have already been "tentative" discussions between Liberal Democrat leaders and disillusioned Labour MPs and peers.
Lord Ashdown's comments come after another turbulent week for Mr Brown and the Labour Party.
On Wednesday a vote on Gurkha settlement rights saw 27 rebel Labour MPs join with the Tories and the Liberal Democrats to inflict Mr Brown's first Commons defeat since becoming Prime Minister.
The next day, ministers were forced to abandon a Commons motion on the reform of the the controversial second home allowance for MPs amid signs that Mr Brown was heading for a politically damaging second defeat within as many days.
These have led to continuing rumblings within the Labour ranks about the party's prospects at the next election.
Former home secretary David Blunkett said the Government needed to avoid any more "self-inflicted wounds", while fellow party heavyweight, Charles Clarke, said that recent events had made him "ashamed" to be a Labour MP.
Deepening gloom on the Labour backbenches was also reflected by veteran left-winger Bob Marshall-Andrews, who said that defeat at the next General Election was "inevitable".
Labour deputy leader Harriet Harman last night warned the party it must stick together.
In a speech delivered last night in Lanark in Scotland, she said that the Government's fate now depended on its ability to maintain party unity.
"Our future as a Government, and as a party, depends on Labour's team - the whole team - in the trade unions, the party members, our MSPs, MEPs, councillors, MPs and ministers," she warned.
"We must all work together to map out our way forward and ensure that we keep Labour in government and keep the Tories out. And unity is vital."