Britain’s third biggest union delivered a huge boost to the campaign for a public vote on Theresa May’s exit terms by throwing its weight behind the push.
It will pile pressure on Jeremy Corbyn to switch Labour’s official policy in favour of a further referendum, ahead of an expected showdown at the party’s annual conference this month.
The Independent has launched its own petition for a Final Say referendum, which has already been signed by almost three-quarters of a million people.
In a video statement, Tim Roache, the GMB’s general secretary, condemned “the mess this government is making of Brexit” when “there is so much at stake”.
“As trade unionists, when we negotiate a pay deal with an employer, we go back to our members and ask them if they’re happy with it,” he said. “Whether they want to accept or reject it
“That’s what people deserve now, because the promises that were made during the referendum campaign are simply not the reality we are facing.”
Mr Roache said people had “voted for change”, but added: “They did not vote for economic chaos or to put jobs and hard won rights on the line.
“That’s why GMB supports your right to decide what sort of Brexit, is the right Brexit. That’s why we support a public vote on the final deal.”
The GMB, which has 620,000 members, backed remaining in the EU at the referendum, although it admitted its members were divided.
It is one of the three big unions – alongside Unite and Unison – that hold influence over Labour, not least because of its significant funding to the party.
It is the first of the three to explicitly back a further referendum, although the Royal College of Nursing, Community and the transport workers’ union, the TSSA, also support one.
Conference delegates instead endorsed a weaker statement, where Unite remains “open to the possibility” of another EU referendum “depending on political circumstances”.
Up to 200 local Labour branches will attempt to make a further Brexit referendum official party policy at the conference in Liverpool, starting on 23 September.
Mr Corbyn hopes to force the prime minister into another general election if her Brexit deal is rejected by parliament this winter, or if she fails to strike any agreement at all.
However, the party has been edging closer to backing a referendum, with both John McDonnell, the shadow chancellor, and Keir Starmer, the shadow Brexit secretary, insisting it must remain an option.
The issue will also be debated by the union movement in Manchester next week, at the TUC conference.
Responding, Brandon Lewis MP, Chairman of the Conservative Party, said: “Rerunning the referendum would take us all back to square one.
“Jeremy Corbyn should stand up to his union paymasters and rule out a second referendum once and for all.”
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