More than 25 Labour MPs have written to Jeremy Corbyn to urge him not to go “full Remain” as the party reviews its stance on another Brexit referendum.
They warn another referendum would be “toxic” and empower the “populist right” in many Labour heartlands.
They call on the leadership to abandon their pursuit of a “perfect deal” and to back an agreement by 31 October.
Mr Corbyn told colleagues on Wednesday afternoon it was “right to demand any deal is put to a public vote”.
Speaking at a shadow cabinet meeting, Mr Corbyn said he would be listening to colleagues and consulting with trade unions before officially setting out Labour’s position next week.
Labour had promised a vote in certain circumstances, specifically if it could not get its own deal with the EU passed by MPs or if there was no general election.
Following the party’s poor performance in the European elections last month, Mr Corbyn said there “had to be a public vote” on any deal agreed with Brussels.
Some senior figures, though, still want him to go further – to campaign for another referendum now and wholeheartedly fight to remain.
In a speech on Monday, deputy leader Tom Watson said Labour’s “ambiguity” over the issue had cost it votes in last month’s European elections, with voters turning to the Lib Dems and other unashamedly pro-Remain parties.
He warned Labour must adopt a stronger position quickly before the election of a new prime minister who could be prepared to take the UK out of the EU without a deal on 31 October.
The BBC’s political correspondent Iain Watson said the MPs’ letter reflected the ongoing tensions within the party on the issue.
Signatories to the letter include Caroline Flint, Lisa Nandy, Jim Fitzpatrick, Stephen Kinnock and Dan Jarvis.
They say “a commitment to a second referendum would be toxic to our bedrock Labour voters, driving a wedge between them and our party”.
They warn the Brexit Party, which ran Labour a close second in the recent Peterborough by-election, poses a “potent” threat to Labour in many of its traditional heartlands.
They point to the “devastating” losses the party suffered in the North East and the Midlands in last month’s council elections and warn of serious electoral consequences for the party if the UK does not leave the EU “without further undue delay”.
Many of the MPs are in Leave-supporting constituencies, but as signatory Caroline Flint points out, even those who are not “share concerns that a Stop Brexit referendum would drive a wedge between our bedrock support and our party”.
A large number of Labour MPs believe any deal on the terms of the UK’s withdrawal needs to be put to a public vote, with the option to remain in the EU on the ballot paper.
Those backing this position include shadow Brexit secretary Sir Keir Starmer and shadow foreign secretary Emily Thornberry.
But Mr Corbyn has always been more cautious, and even after coming third in the European elections, he said another referendum was still “some way off”.
In his opening remarks to Tuesday’s shadow cabinet meeting, he told his frontbench team Labour’s evolving position on a referendum was “in line” with the stance agreed by party members last year that a public vote was “an option” if other avenues to prevent a no-deal exit were exhausted.
“I have already made the case… that it is now right to demand that any deal is put to a public vote,” he said.
“A ballot paper would need to contain real choices for both Leave and Remain voters. This will, of course, depend on Parliament.”
Brexit: Labour MPs urge Corbyn not to go ‘full Remain’}