In a challenge to Jeremy Corbyn, the co-operative party – the 38 MPs sitting in Labor in the House of Commons – called on Britain to remain in the single market and in a customs union with the EU.
The move, agreed at the Bristol party conference, is also a serious blow to Theresa May, as it means that her deputies are virtually certain that they will vote against any agreement that she submits to Parliament later in the year.
The Labor Party has stopped supporting another EU referendum, arguing instead that there should be a general election if the May Agreement is rejected by the Commons.
But one in six Brexit resolutions, overwhelmingly passed at the Coperative Party conference, said: "The terms of a Brexit agreement were unknown at the time of the referendum in 2016. Once the negotiations are finalized, a public vote should be taken We should not leave the EU on the proposed terms. "
Another calls for "Britain's continued membership and access to the single market through the European Economic Area Agreement".
Cooperative Party leader Gareth Thomas said: "Members of the Cooperative faction today voted to put the British people back in the center of the Brexit process by supporting a vote on the final Brexit deal, and so is our party It was clear that no deal is not an option.
"As we work to create a United Kingdom where wealth and power are shared, it is important that Brexit does not lead Britain to a path of greater inequality, insecurity and isolation, instead we need a UK with cooperative values such as democracy, Equality and solidarity in their hearts, that's at stake. "
Eloise Todd, leader of the Best For Britain campaign, who called for another referendum, said: "It is good news that the official position of the Co-op party is to make the final decision on EU membership To let people.
"The party includes key MPs from across the Labor Party and recalls the position Labor put forward at its conference in late September: If elections are not possible, Labor and Co-op MPs are open to a referendum on the Brexit deal, to give its members, voters and citizens the right to choose between the intergovernmental agreement and our current EU conditions.
"We urge the Prime Minister to listen to the growing number of people and organizations who say people should be at the helm."