Momentum, the Jeremy Corbyn supporter group that has been at war with itself for months, moved to kick out its hard-left faction on Tuesday night by imposing a new constitution that would require members to join the Labour party.
But now rebel left-wing members are fighting back, telling BuzzFeed News they intend to circumvent the internal leadership "coup" by exerting control over the group through other means and continuing to hold rival leadership meetings.
New details have emerged of how Momentum founder Jon Lansman and his allies cemented control over the organisation with the apparent knowledge of the Labour leader's office.
A new constitution for Momentum was proposed by Lansman through an unexpected email to the dozen members of Momentum's steering committee shortly before 8pm on Tuesday night, asking for their approval.
An hour later Lansman told the email list that it had received sufficient support and by 9.30pm an email had been sent to Momentum activists and the media, announcing the introduction of the new constitution.
Jill Mountford, a member of the steering committee who was kicked out of Labour for being a member of the Trotskyist Alliance for Workers' Liberty, told BuzzFeed News she would continue to be active despite facing exclusion from Momentum as a result of the changes.
"I’ve not seen anything quite like it," she said. "At twenty to eight last night, without any notice, Jon Lansman sent out an email. If you weren’t at home, you weren’t available, you would not have been able to take part in this."
She said rebel members of the steering committee, previously Momentum's governing organisation, would continue to meet as planned on Wednesday night despite the committee officially ceasing to exist. She also floated the prospect of hard-left activists working to link local Momentum groups while circumventing the official Momentum leadership.
"Jon Lansman organising a coup by email is not going to deter a whole host of us – far from it," said Mountford.
"We’re going to discuss what we do next. There’ll be a couple of thousand people who will not give up, I think we need to set up a local democratic structure.
"The lesson that Jon Lansman is teaching a new generation of political activists is shocking, he's teaching them to have a complete disregard for democratic structures."
Under the proposals, Momentum members will have to join Labour by 1 July or quit the group, while Momentum will also attempt to formally affiliate to Labour, ending its position as a vehicle for the wider British left.
But Mountford said there was not much the Momentum leadership could do to stop her being involved with local groups and pledged to organise a conference to overturn Lansman's changes: "Unless they’re going to take me out, what are
they going to do stop me?"
Lansman told BuzzFeed News that the decision to impose a constitution on the group was necessary, even if he didn't give any advance warning of the proposed changes to members of the steering committee: "Given the level of acrimony it seemed better if we solved it by email and we did. I wouldn’t say it was short notice.
"There have been divisions over the structure which have been the case for a while. We circulated the survey before Christmas and gave people time to get a proportionate response. We prepared for this possible outcome.
"Because we had no constitution, we had no agreed legal mechanism for changing the rules; we didn’t have rules to change. This was the only way to do it."
However, Michael Chessum, another member of the Momentum steering committee, who served as the group's treasurer, said he was "deeply alarmed" by Lansman's actions.
"When tiny groups of people on committees take decisions they are clearly not entitled to make – like abolishing all of our democratic structures by email vote in the space of an hour – that isn't just wrong, it's also demoralising for members and activists. There absolutely is a compromise solution to this crisis – and it has to be salvaged."
The dispute centres on whether Momentum should be organised along the lines of traditional left-wing group with delegates, or through a decentralised membership structure. Hard-left groups active within Momentum preferred the former, with suggestions Trotyskite groups were on the cusp of taking complete control of the group.
A separate Momentum source confirmed there had been coordination between the group and Jeremy Corbyn's team ahead of Lansman's email: "There’s been discussions between people in the leader’s office and people in Momentum about things. It would be wrong to characterise the whole thing as a fully coordinated thing – there’s been some coordination.
"Any situation was going to be far from ideal. This may resolve it in a way which causes short-term problem but long-term gain."
A spokesperson for Momentum said the new constitution would ensure it is a "truly members-led movement" that would empower local activists to directly vote on constitutional amendments and campaign priorities via a "digital democracy platform".