Deputy leader agrees with Keir Starmer that new referendum will be needed for deal to pass

Labour is still a “remain and reform party” over EU membership, Tom Watson has argued, as he said it seemed inevitable that a confirmatory referendum would be needed for the party’s MPs to agree to any Brexit deal.

Speaking after the shadow Brexit secretary, Keir Starmer, told the Guardian that up to 150 Labour MPs would reject an agreement that did not include a second referendum, Watson said he believed this figure seemed credible.

Watson, Labour’s deputy leader, told BBC Radio 4’s Today programme that even though talks with the government over a compromise deal were still ongoing – they are due to resume on Monday – it “would be difficult” to get it through parliament without a new public vote.

“I think the difficulty is just parliamentary arithmetic,” he said. “Keir Starmer has alluded to this today as well, John McDonnell did last week. The whipping arrangements for these deals are very difficult, as MPs have hardened their positions within their parties.”

In a sign of the very different approaches within the shadow cabinet, when asked if Labour was now a Brexit party, something the shadow international trade secretary, Barry Gardiner, concurred with on Sunday, Watson took a different approach.

“We are a remain and reform party, but obviously when it comes to a deal, people could form their own view,” he said.

Watson said he still thought getting a Brexit deal though the Commons was the best option, but had come round to the idea of a second referendum for practical reasons.

“I’ve wanted a deal. I reluctantly came to the view that there should be a confirmatory ballot, because I thought it was the only way we would break the impasse,” 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 difficult.

“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.”

Later on Monday, Watson was due to make a speech marking the 25th anniversary of John Smith’s death in which he was to argue that the former Labour leader, as a pro-European internationalist, would have also backed a second referendum.

“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,” Watson was to say.

In an interview with the Guardian, Starmer said a second referendum would be needed to buoy up any deal with the government.

“A significant number of Labour MPs, probably 120 if not 150, would not back a deal if it hasn’t got a confirmatory vote,” he said. “If the point of the exercise is to get a sustainable majority, over several weeks or months of delivering on the implementation, you can’t leave a confirmatory vote out of the package.”

He said finding a parliamentary majority for any deal, whatever the circumstances, was “very difficult”, and suggested he could not sign up to any agreement if he feared it would fail.

“It has got to be something truly deliverable,” he said. “For many of my colleagues, they have made it clear that they will not vote for a deal without a confirmatory vote attached to it. So if you want that stable majority, that has to be taken into account. And without it, it is impossible to see how the numbers would stack up.”

Also speaking on the Today programme on Monday, the communities secretary, James Brokenshire, dismissed reports that the talks with Labour were doomed.

“These talks are very serious, yes – we wouldn’t have committed all of the time and effort on all sides in relation to this. They have been constructive, they have been detailed,” he said.

Starmer’s comments were, Brokenshire added, “a slightly different message to the core message that the Labour party has been giving about a second referendum”.

Brokenshire said he believed a second vote was a bad idea: “These talks are about how to give effect to the referendum, how we give effect to leave the EU, not somehow reopening the debate all over again.”