Jeremy Corbyn has come under mounting pressure to back a second referendum after Labour ’s European elections pummelling.
Two of the Labour leader’s closest allies – big hitters John McDonnell and Diane Abbott – called for changes to his strategy after the party lost half its MEPs.
And Mr Corbyn promised he was “listening very carefully” to arguments both for and against a public vote.
Shadow Chancellor Mr McDonnell, a hugely influential figure, said another referendum was the “only option now”.
He insisted forcing a general election – Mr Corbyn’s preference – was now “highly unlikely” before the October 31 Brexit deadline.
And Shadow Home Secretary Ms Abbott insisted the party “needed to take a clearer line” on the issue.
As many of his MPs urged him to be bolder, Mr Corbyn said he was “ready” to support a fresh public vote.
Labour sources claimed his remarks represented a “shift in tone and emphasis” from his previous position that the option should be used only to prevent a damaging hard Brexit.
One Shadow Cabinet minister told the Mirror: “We are edging towards a second referendum as policy.
“The issue is how you trigger one with a Tory Brexiteer PM who may not bring a Withdrawal Bill to the Commons which we could amend to include one.”
But some of Mr Corbyn’s key aides want him to stick to his fence-sitting policy amid fears that the Remain position of a second vote could cost Labour scores of seats in the North and the Midlands.
A flood of Remain voters abandoned Labour for the Lib Dems and Greens in last Thursday’s European vote while Leave voters switched to Nigel Farage’s Brexit Party.
It has left both Labour and Tory MPs on both sides fearing another backlash at the next general election.
In a devastating night for the party, Labour was left with just 14.6% of the vote in third place. Even in Mr Corbyn’s Islington backyard it only managed to come second to the Lib Dems.
Party insiders say in the coming weeks he will consult members, who overwhelmingly back Remain, and unions on the party’s stance.
He has promised “conversations across the party divide” to find a way forward.
But he is likely to stop short of an all-member ballot or a special conference to formally shift position, as demanded by deputy leader Tom Watson, who believes waiting until party conference in September will be too late.
In a letter to MPs, Mr Corbyn wrote: “It is clear the deadlock in Parliament can now only be broken by the issue going back to the people through a general election or a public vote.
We are ready to support a public vote on any deal.”
But some senior Labour figures are demanding unconditional backing for a second referendum – whether or not there is an EU deal on offer.
Shadow Foreign Secretary Emily Thornberry was among those who blasted the party’s “unclear strategy” and demanded a fresh vote.
And Shadow Brexit Secretary Keir Starmer said the “only way” to break the impasse was to have one with Remain on the ballot.
Mr Watson said: “Labour urgently needs to re-think its Brexit position and realign with members and voters.”
But it was the hardening position of Mr McDonnell that underlined the importance of the shift.
He said a referendum was now “inevitable” because the Tories would not back a general election after their own hammering last week. And he insisted it should take place in any circumstances.
He said: “Our only option now is to go back to the people in a referendum and that is the position we are in now.”
The Mirror understands he has also argued in private for the party to commit to one.
One Labour source, however, said: “There are others who think a general election is more likely than a second referendum, especially if you’re facing a no-deal scenario.”
Ms Abbott, one of Mr Corbyn’s oldest friends, also said the poor result was “a clue something is wrong with our strategy”.
She added: “We need to listen to our members and take a clearer line on a public vote.”
Labour insiders also revealed that Mr Corbyn, whose Islington seat had one of the highest Remain votes in the country, considered making a second referendum a condition of cross-party Brexit talks with the Government, but was talked out of it by aides.
The party suffered poor results across the country, last week coming fifth in Scotland and third in Wales, where leader Mark Drakeford said he wanted a new vote with an option to Remain.
But key Corbyn lieutenant Richard Burgon insisted Labour had the right approach in seeking to appeal to both Leavers and Remainers.
And Labour MP for Ashfield, Gloria De Piero, urged colleagues not to let a referendum “wreck” the party.
“[It] would be an effective ending of Labour’s historic coalition of working-class, middle-class, city and non-city voters,” she said.
Unions also entered the fray with Unite chief Len McCluskey, another Corbyn ally, accusing those in favour of a second referendum of trying to launch a coup against the party leader.
“There are some rushing to advance other agendas but are doing so to undermine Jeremy Corbyn . They will be seen for what they are and never forgiven by the members,” he said.
But other union chiefs insisted a second referendum was the only way to avoid catastrophic defeat at a general election.
Dave Prentis, general secretary of Unison, the country’s biggest union, said: “If Labour is going to win
the next election, it needs to understand that ambiguity and division aren’t appealing.”
Manuel Cortes, chief of the Transport Salaried Staffs’ Association, added: “I supported Jeremy Corbyn for the leadership of our party whilst others hedged their bets.
“Nonsense to suggest that having a policy which chimes with our members is some sort of coup – time to support our brilliant party activists on Brexit.”