A controversial Momentum recruitment drive to get supporters to join Unite in order to back the re-election of Len McCluskey as the union’s leader failed to make any significant impact on the membership, according to figures leaked to the Guardian.

An extra 659 people joined as community members in December compared with the previous month, part or all of which may be the result of the campaign group asking its supporters to join Unite to vote to keep McCluskey, a key ally of Labour leader Jeremy Corbyn.

In total the union has 1.4 million members, though only about 15% voted in the last election of its general secretary in 2013. Were all the new members to vote, the turnout could be expected to increase by around 0.3%.

The battle to become leader of Unite is being seen as a proxy war for control of the Labour movement between Corbyn’s supporters and opponents. McCluskey, standing for a third term in office, is facing criticisms from his main rival Gerard Coyne for spending too much time on Labour’s internal politics.

Unite is the party’s biggest donor and has steadfastly maintained support for Corbyn in the face of poor polling and byelection results.

In an email to its members sent in December, Momentum said: “During the summer, Unite the Union – led by Len McCluskey – threw its support behind Jeremy Corbyn’s leadership campaign … Now, Len McCluskey needs our support.”

Len McCluskey Photograph: Rick Findler/PA

Some Momentum activists had expressed discomfort on social media about the email and in comments under the Facebook video that urged its members to join Unite. Simon Hannah, a prominent activist from Wansdworth Momentum, said the movement should not view trade unions as political clubs.



“Momentum is urging people to vote in an internal election in a trade union without any consultation with the membership,” he wrote. “Moreover, asking everyone to join Unite is ridiculous and undermines the very basis of what trade unionism is. Unite is not some playground that people should join on a whim just to take part in an election.”

Hannah said the email made it appear as if members of the movement “were simply given their marching orders.”

A Momentum spokesperson said: “Under Len McCluskey’s leadership, Unite has taken on unscrupulous employers such as Argos and Sports Direct and won a better deal for workers, which is why Momentum has encouraged our members, many of whom are also Unite members, to support his re-election.”

McCluskey triggered a leadership contest last month by giving notice of his resignation, then immediately announced he would be standing for a third term. The election will take place in the spring, with the result announced on 28 April.

Coyne hopes to win the support of members concerned by Corbyn’s anti-Trident stance, given that thousands of Unite members work in the defence industry.

A spokeswoman for the Unite4Len campaign said: “Unite does not comment on who is joining our union. The only accurate figures for membership are those given to our EC, which will not be until March. Any other figures are not accurate.”

• This article was amended on 11 January 2017. We said the turnout could be expected to increase by around 4% were all new members to vote. This figure should have been 0.3%. This has been corrected.