Jeremy Corbyn is under mounting pressure to promise a second Brexit referendum in Labour's European Elections Manifesto.
Some 89 Labour MPs and MEPs have written to the party leader urging him to promise a "confirmatory vote" if EU Elections go ahead next month (MAY).
It comes ahead of a crunch meeting of the party's ruling body on Tuesday, which will set the party's manifesto for the poll.
The letter, organised by left-wing Love Socialism Hate Brexit group of MPs, notes: "Labour has already, rightly, backed a confirmatory public vote. The overwhelming majority of our members and voters support this, and it is the democratically established policy of the party.”
It adds: "We need a message of hope and solidarity, and we need to campaign for it without caveats.
"To motivate our supporters, and to do the right thing by our members and our policy, a clear commitment to a confirmatory public vote on any Brexit deal must be part of our European election manifesto.
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"We understand the many different pressures and views within our movement, but without this clear commitment, we fear that our electoral coalition could fall apart.”
A row was brewing yesterday (FRI) after it emerged the party had produced an election leaflet which failed to mention a second EU referendum.
The flyer for the May 23 EU elections makes no mention of the proposal - despite last year's party conference agreeing it would be an option on the table.
Meanwhile the leaflet says Labour will negotiate "a better deal with Europe" under its own plan for Brexit.
One Remain-backing MP told the Mirror the leaflet had gone down "like a cup of cold sick".
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Another, Neil Coyle, said: "It's being posted out after a dodgy sign off and will do untold damage to our Party and does not reflect members' views or agreed policy.
"Another massive let down and shows little learnt since The Independent Group formed."
Labour's Shadow Cabinet, which was reportedly not consulted over the leaflet, will also meet on Tuesday morning to debate the party's manifesto for the EU elections.
The ruling NEC which includes senior MEPs, union chiefs and members' reps will then meet later on Tuesday to thrash out the manifesto.
A Labour Party spokeswoman said: "It is a short pre-manifesto leaflet to introduce our candidates and set out our commitment to Leave and Remain voters to bring our country together.
"It highlights how the Tories' chaotic handling of Brexit has left our country in crisis and how our MEPs will fight for proper investment in communities, housing, jobs and industries
"Our full manifesto, which will address the issues of a Brexit deal and the circumstances of a referendum, will be published after the local elections."
