Two senior Labour frontbenchers have thrown their weight behind calls for a second referendum on a cross-party Brexit deal.
Labour deputy leader Tom Watson, MP for West Bromwich East, said Labour was a “remain and reform” party.
And Shadow Brexit secretary Sir Keir Starmer warned it was “impossible” to see how any Brexit deal could win the backing of a majority of MPs unless it included plans for a “confirmatory vote”.
It comes after Barry Gardiner, Labour’s Shadow International Development Secretary, suggested Labour was committed to leaving the EU, in an interview on Sunday.
Mr Gardiner said: “We believe it’s important that as a country we respect the promises that we made and the democratic decision of the people.”
Mr Watson told BBC Radio 4’s Today programme that he believed the House of Commons would probably only vote for a Brexit deal if it also included the promise of a second referendum.
He said: “If a deal could be found that inspires enough votes in Westminster then fine, but it seemed to me that that’s very, very difficult.
“And so my idea of a confirmatory ballot is not a religious point or a point of ideology, it’s just how do you get an outcome, how do you sort this out?
“And one way to do it are these two minority positions – the Prime Minister’s deal and those that think the people should have a say on the deal – plug them together and you build a majority.”
Later tonight, Mr Watson will suggest that former Labour leader John Smith, one of the most beloved figures in the party’s history, would have backed a second referendum.
Speaking at a lecture in Westminster to mark the 25th anniversary of the death of the former Labour boss, Mr Watson will say: “If John was alive today, to witness the great damage this process is wreaking on country and our public debate, I have no doubt that he would have taken a stand very similar to that of his deputy, Margaret Beckett, and backed a People’s Vote as a way out of this destructive mess.”
John Smith died of a heart attack in 1994.
Meanwhile, Sir Keir told the Guardian newspaper that “probably 120 if not 150” of the party’s 229 MPs could vote against the deal unless it was linked to a second referendum.
Debate within the Labour Party focuses on whether the party should back a “confirmatory vote” on any proposal to carry out Brexit – or only back a public vote if the Conservative Government somehow succeeds in convincing MPs to approve its withdrawal agreement.
Opinion polls suggest Labour could come second in the European elections on May 23, with Nigel Farage’s Brexit Party in first place.
Labour campaigners are attempting to convince anti-Brexit voters to back their party – despite its ambiguous position on whether to press ahead with leaving the EU – to avoid handing victory to the Brexit Party.
Meanwhile, some polls show the Tories right down in fifth place, behind the Liberal Democrats and Green Party.
The latest survey from YouGov for the Times, asking people how they intend to vote in the European Elections, has the Brexit Party on 34%; Labour on 16%; Lib Dems on 15%; Greens on 11% and the Conservatives on 10%, with Change UK, the anti-Brexit party formed by former Labour and Tory MPs, on 5%.
Talks between Labour and the Conservatives about a Brexit deal are continuing.
Foreign Secretary Jeremy Hunt said this week would be “crunch week” for cross-party Brexit negotiations, but rejected the possibility of a second referendum.
Speaking outside the EU’s Foreign Affairs Council, Mr Hunt said: “From a Conservative point of view, we’ve always said that we think that would be a betrayal of what people voted for, and we want to implement the first referendum.
“But lets see where these talks go to.”
Elsewhere, the Chancellor’s parliamentary aide, Tory MP Huw Merriman, said the Tories will suffer “an absolute mauling” in next week’s European Parliament elections.
“The public will blame the Conservative government because we were the party that brought forward the referendum,” Mr Merriman, who backs a second referendum, told BBC Radio 4’s Westminster Hour on Sunday night.
“And so for those that didn’t want it and wanted Remain, they’ll blame us for having tried to take us out.
“And for those that voted to leave, they’ll blame us for having not got the country out of the EU.
“We’re at the perfect storm, so yes, I think we’ll get an absolute mauling.”