The Labour leader will today back a move to change the party’s Brexit policy to one of supporting another vote on any deal negotiated, according to The Times.
Mr Corbyn, who has so far resisted the move, is set to discuss the paper recommending the policy by his head of policy, Andrew Fisher, with members of the shadow cabinet.
A senior Labour source told the Times that the shift in policy was “a moment”.
The move would pit Labour against Tory leadership candidates including Boris Johnson, Jeremy Hunt and Michael Gove, who have all vowed to deliver Brexit.
Fellow hopeful Rory Stewart insists he would successfully get Theresa May’s deal through parliament.
Labour, which along with the Conservatives saw its support slump at the European elections as voters expressed their frustration over Brexit deadlock, is divided over whether to unequivocally support holding a second referendum.
Mr Corbyn has so far only said the option of another Brexit vote should be kept on the table if changed to Theresa May’s deal were not made, with a general election the next option.
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A shadow cabinet minister said that the results of the European elections have forced Labour to change tack.
They said: “It is a question of getting on the front foot now or having it forced upon us at conference.
“I’ve previously been sceptical but I don’t think there is a choice any more.”
Labour’s deputy leader Tom Watson said the party should throw its eight behind a second referendum as “the least worst option”, and that they should campaign for Remain.
Other senior figures, including shadow Brexit secretary Sir Keir Starmer and shadow foreign secretary Emily Thornberry, have also urged the party to back the policy.
However, the move is likely to face resistance from many Labour MPs who represent areas that voted to leave the EU.
Another Labour source said that Mr Corbyn’s previous hesitance to hold a second vote may also make it difficult to persuade Remainers he is genuinely for what some have dubbed a People’s Vote.
Mr Corbyn himself said after the European elections that his preference was still a general election over another referendum.
The move to back a second vote would put the party directly at odds with potential Prime Minister Boris Johnson, who has committed to leaving the EU by October 31 - with or without a deal.
Mr Johnson, the favourite to win the Tory leadership contest, said last week that he would rather leave with a deal, but was prepared to exit without one.