Labour Movement for Europe, the pro-EU group affiliated to the party, has nominated Keir Starmer in the race to be the next leader.
The society, which describes itself as “the home of the pro-Europeans in the Labour and trade union movement” gave the shadow Brexit secretary its backing, saying he “understands the importance of keeping as close as possible a relationship with the EU”.
It has also backed Ian Murray, Labour’s only MP in Scotland, for the deputy leadership.
The news comes on the same day that the Community union endorsed Starmer, the early front-runner for the job, but in their case with Angela Rayner as deputy leader.
Anna Turley, the former MP for Redcar who chairs the movement, said: “Our executive has decided to nominate Keir Starmer and Ian Murray because of their strong pro-EU values and the fact that we think they are in the best place to take Labour to victory at the next election.
“Keir led Labour’s Brexit position with skill and diligence, guiding the party to the position we adopted at conference in support of a confirmatory referendum.
“His personal position as stated in the general election was for Labour to clearly campaign to Remain should there have been a referendum. He worked hard to keep all sides of the debate within our movement together in a difficult and fractious period.
“As we leave the European Union, Keir understands the importance of keeping as close as possible a relationship with the EU to protect people’s jobs, their rights and the NHS and environment.”
Murray is the only Labour MP in Scotland, which voted firmly against Brexit, for a second consecutive election.
Turley said: “He has not only survived because of his ability to communicate and campaign but because he has spoken up for pro-European values.
“Ian was part of the successful court challenge against Boris Johnson’s unlawful prorogation of Parliament, the co-chair of the Labour Campaign for the Single Market and a strong supporter of a people’s vote. He understands that even after Brexit our ties with Europe must remain strong.
“We are confident the two will take our pro-European and internationalist values forward.”
The movement’s honorary president is the former Labour leader Neil Kinnock.
Giving Starmer his union’s backing, Community general secretary Roy Rickhuss said his experience and vision were “what the Labour Party needs to rebuild, win back the trust of voters, and lead a transformative Labour government”.
Referring to Rayner, he said: “We believe she will help unite our fractured party, reinvigorate the Labour movement, and lead us into government.”
The union also urged its members in constituency Labour parties (CLPs) to help ensure that Murray made the final ballot for the deputy post.
Candidates are required to have won the nomination of three Labour affiliates, including at least two unions, which amount to at least 5% of affiliate members.
The only other route on to the ballot is by receiving nominations from at least 5% of CLPs.
Both Unison and Usdaw have already given Starmer their backing in the race to replace outgoing leader Jeremy Corbyn in April.
It emerged today that the Corbynite candidate for the leadership, Rebecca Long Bailey, had said that she dismissed as “bollocks” the idea that the country did not want socialism after Labour’s election defeat.
The shadow business secretary said she had been shocked at the outcome and found herself questioning whether Jeremy Corbyn’s brand of politics could ever win.
“It was as if everything I believed in was being ripped up before my very eyes, that everything we fought and we’re so proud of was suddenly invalidated; no one wanted us, no one wanted socialism,” she said. “And then I pushed that thought out of my head, because I thought ‘That’s bollocks’.”
A recording of her comments, made on Saturday night, was leaked to HuffPost.