Labour is set to back a referendum on the terms of the UK's exit from the EU, but only one that offers a 'deal or no deal' choice - not a chance to reverse Brexit.
The motion that will be voted on by party members on Tuesday commits Labour to supporting a public vote if it cannot force a general election, saying the party should consider "all options remaining on the table".
However, Shadow Chancellor John McDonnell sparked anger by ruling out the possibility that remaining in the EU could be an option in a new referendum.
Mr McDonnell said a general election would be "the real People's Vote" on Brexit. "My understanding of what the discussion, certainly within my party has been all about, is: respect the referendum but the deal that comes back, if it's not acceptable to Parliament, we should have a general election or keep the option of a People's Vote on the deal on the table," he told ITV's Good Morning Britain.
"In that case it will be about whether you accept the deal or not or whether you send people back to negotiate a proper deal."
And Mr McDonnell told BBC Radio 5 Live: "We argued for Remain in the past but we lost that vote so we have to respect that.
"All the polling that we have seen is that the country is still pretty split down the middle.
"My big worry is that if we go for a referendum which is seen as just a simple re-run we could divide the country again, we could get almost the same result or if it's slightly different that people demand another referendum."
Labour MP David Lammy said it would be "farcical" to offer a referendum between "no deal or a bad deal". The referendum "absolutely must include the right to remain in the EU", he said.
Jeremy Corbyn has said he will be "bound" by the decision of party members in a vote on Tuesday.
Leading trade unionists and Labour's shadow Brexit Secretary agreed the wording of the motion based on submissions from scores of constituency parties during a four-hour meeting that broke up just before midnight on Sunday.
The key paragraph in the document states: “If we cannot get a general election Labour must support all options remaining on the table, including campaigning for a public vote.
“If the government is confident in negotiating a deal that working people, our economy and communities will benefit from, they should not be afraid to put that deal to the public.”
An early draft proposing “a public vote on the terms of Brexit” was rejected in favour of a broader framing of a new referendum, leaving open the possibility of an option to stay in the EU being on the ballot paper.
However, the motion does not specify which question Labour would seek to ask the public in any such vote. On Sunday, Unite general secretary Len McCluskey spoke out against any attempt to keep the UK in the EU.
Liberal Democrat Brexit spokesman Tom Brake MP said: “Labour’s leaders are aiding and abetting Theresa May on Brexit. They’ve spent two years backing the Tories’ catastrophic Brexit and are even now trying to ignore their own members who want a People’s Vote with the option to remain in the EU.
READ MORE: Labour braced for showdown over Corbyn’s Brexit position
“It beggars belief that McDonnell and co are spending so much time trying to trick and stitch up their own conference, rather than campaigning for an exit from Brexit to protect jobs and services in the UK.
“The only choice a ‘deal or no deal’ vote gives people is which foot to point the gun at."