Labour looks set to back the option of a fresh referendum on European Union membership, which could include the option of voting to remain in the UK, when the motion is put to a vote at the party's conference in Liverpool.
Under the terms of the motion set to be voted on at the conference on Tuesday, if Labour cannot force an early General Election it will “support all options remaining on the table, including campaigning for a public vote”.
Shadow Brexit secretary Sir Keir Starmer said the scope of the motion was “wide enough to encompass the option of Remain” in any referendum.
His comments came after shadow chancellor John McDonnell signalled he would want any second Brexit referendum to be limited to choosing how to leave the EU - effectively giving people a choice between accepting the Government's deal with the EU, or choosing no deal.
Mr McDonnell also said the exact wording of any referendum would be decided on by Parliament.
Labour already appears set to reject Theresa May’s Brexit plan, claiming it fails to meet the party’s six tests for any deal.
If Labour votes against the Prime Minister's Brexit plan in Parliament, it would be unlikely to pass through the House of Commons, and if this were the case, Labour hopes Mrs May would then call a General Election.
The party argues that this would allow for more debate on the issue of Brexit, with both parties setting out their stalls, and the public then voting for whichever party's plans they prefer.
Sir Keir said if Mrs May’s did not call a General Election, then Labour would keep all options open, including pushing for a referendum on the deal.
Speaking on Tuesday, Sir Keir said no deal could "cost jobs", "the pound would begin to drop", and there would not be any "arrangements for security and counter-terrorism".
He added: “We don’t want to face that situation and we have got a duty to do something to stop it and that’s why the option of a public vote is important as something that may have to happen when we get to that stage.”
What are Labour's six tests which a Brexit deal must pass?
A “strong and collaborative” future relationship with the EU
The “exact same benefits” as single market and customs union membership
Fair management of migration
Defence of rights and protections
Protection for national security
Delivering for all regions and nations of the UK