Tom Watson will pledge to vote for Theresa May’s beleaguered Brexit deal to prevent the UK crashing out of the EU if she vows to let the public have a say on it.
Labour’s deputy leader will tell a rally that he has reluctantly come to the view that the only way to resolve the current impasse is “for people themselves to sign it off”.
Mr Watson is set to address the Put It To The People March in Parliament Square on Saturday, where hundreds of thousands of campaigners will call for a second referendum.
Labour officially supports a second referendum, but has not said whether it would back the Prime Minister’s deal on the condition it is put to a public vote.
Mr Watson will tell the crowds in Westminster: “Brexit is currently stuck in the pipework of Parliament, with MPs split, completely unable to agree or find a way forward.
“The current impasse is not working for people who voted to leave or people who voted to stay. I really don’t think Parliament will be able to resolve this.
“That’s why I’ve come to the reluctant view that the only way to resolve this and have legitimacy in the eyes of the public is for the people themselves to sign it off.
“It can only bring closure if we’re all involved in making the decision.
“It can only begin to bring the country back together again if we all have a final say – and then live with the result.
“So, I have an explicit message for Theresa May: I will vote for your deal or a revised deal you can agree with my party. I will help you get it over the line to prevent a disastrous no deal exit. But I can only vote for your deal – or any deal – if you let the people have a vote on it too.
“That’s why I’m proud to be marching. I trust the people I represent. And only they can sort this mess out.”
Scottish First Minister Nicola Sturgeon, former deputy prime minister Lord Heseltine and London mayor Sadiq Khan will also address the protest.