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.
Labour has promised a vote if it cannot get its own deal with the EU passed by MPs or if there is no general election.
The shadow cabinet is currently discussing whether to soften Labour’s stance amid calls for it to back a referendum in any circumstances and campaign wholeheartedly 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”.
Party divided
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. Despite Labour coming third in the European elections, he said that another referendum was still “some way off”.
And MPs in Brexit-backing constituencies, including the party chairman Ian Lavery, have warned another referendum would be a betrayal of the 17.4 million people who voted to leave the EU in the 2016 referendum.
