Labour’s deputy leader, Tom Watson, said he “feared” traditional Labour supporters had ditched the party because of its “mealy-mouthed” stance on a second referendum.
Writing in The Observer, he said: “For our party’s sake, but most of all for Britain’s sake, Labour needs to find some backbone on Brexit, find our voice – and do it fast.
“Our performance (in the European elections) is a direct result of our mealy-mouthed backing for a public vote on Brexit when it is being demanded loud and clear by the overwhelming majority of our members and voters.”
At Labour’s conference last year an overwhelming majority backed a so-called People’s Vote, however the team at the top is split over whether to push for it, with figures such as Shadow Foreign Secretary Emily Thornberry appearing more enthusiastic about the suggestion that Mr Corbyn.
Ahead of the European elections, Jeremy Corbyn saw off an attempt by pro-EU members to commit the party to a second referendum on the Brexit issue.
The party’s ruling committee agreed it would stick to the wording of a motion passed by Labour conference last year, which keeps a public vote on the table as a last option.
But this decision was made by a “small number of people” and should instead be made my party members, Mr Watson said.
The deputy leader is supporting calls for Labour’s Brexit policy to be changed before the autumn party conference.
He said: “I fear that unless our policy on Brexit changes we will not have the opportunity to be the radical reforming government that so many millions of people in our country need.
“The campaign to change that begins now.”
Responding to Tom Watson’s comments, John McDonnell admitted to Sky News today that Labour is braced for a “good kicking” in the European Parliament elections and will pay an electoral price for their stance on Brexit.
But the shadow chancellor told Sophy Ridge on Sunday: “It would have been easy to go to one side, go to the Remain side and ignored all those people who voted Leave – that’s not the nature of our party.”