Fresh divisions are set to open up within Labour after deputy leader Tom Watson called on the party to back a new Brexit referendum before a general election.
In a speech today in London, Mr Watson said a single-issue Brexit election may not break the deadlock in Parliament – something he said only a second referendum could achieve with certainty.
He also argued that if a referendum were to follow an election, then Labour should commit "unambiguously and unequivocally" to campaign for Remain.
Mr Corbyn has said an incoming Labour government would hold a new referendum with Remain and a "credible" option for Leave on the ballot paper.
However he has yet to say which side he would support.
Mr Watson argued it is not too late for Labour to win back Remain voters put off by confusion over the party's position on Brexit.
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"My experience on the doorstep tells me most of those who've deserted us over our Brexit policy did so with deep regret and would greatly prefer to come back; they just want us to take an unequivocal position that whatever happens we'll fight to remain, and to sound like we mean it," he said.
"If we did it we could win, whereas if we don't I fear we won’t."
Mr Watson said that so much has changed since the original referendum in 2016 it was "no longer a valid basis" for determining Britain's future and the priority should be a new public vote before an election.
"Very difficult though it was, I and many others respected the result of the 2016 referendum for a long time," he said.
"But there eventually comes a point – and we are very far past it now, well into the fourth year since the referendum – when circumstances are so changed, when so much new information has emerged that we didn't have in 2016, when so many people feel differently to how they felt then, that you have to say, no, that years-old plebiscite is no longer a valid basis on which to take such a momentous decision about the future of the United Kingdom.
"The only proper way to proceed in such circumstances is to consult the people again.”
Shadow Brexit secretary Sir Keir Starmer stopped short of fully endorsing Mr Watson, but said Labour is united around the idea that another referendum on Brexit should be included in the party’s manifesto.
Speaking to BBC News, Sir Keir said: “The Labour Party is in good spirits, we have just had a very good week.
“We have defeated the Government six times, we are united around the idea there should be a referendum on any outcome this Government puts forward, and that we should have a referendum in our manifesto, and that remain should be one of the options in that referendum.”
Responding to Labour’s plans, Conservative Party chairman James Cleverly said: "Labour's deputy leader makes clear Labour want to cancel the referendum result.
"This latest trick would mean delaying Brexit again for up to a year, handing over £250 million a week to Brussels for no purpose. Labour are running scared of an election and only offer more dither and pointless delay.
"Only Boris Johnson and the Conservatives will deliver Brexit by 31 October, no ifs or buts, so we can move on and focus on the issues that matter to people – investing in the NHS, reducing violent crime and cutting the cost of living."