I don’t even like cupcakes that much – and I despise the practice, which is sadly becoming more widespread, of playing out the left’s internal squabbles on the pages of newspapers. But the picture painted by leaked emails from Momentum’s steering committee last week, in which I urged my colleagues to “eat cupcakes and think about butterflies” in a frustrated plea to them to step back from the brink of a split, is worthy of elaboration. The coup currently under way in Momentum tells us something bigger about the need for the left to rethink its strategy.

Momentum’s leadership has imposed a constitution on the organisation, abolishing the democratic structures that have been developing over the past year and cancelling its founding conference, where members were due to debate its future. The stated goal of the new constitution is to ensure that Momentum does not replicate the Labour party, clearing the way for it to affiliate as a socialist society. Ironically, under the new rules Momentum will be governed by a national coordinating group with representatives from members, local government, MPs and other stakeholders – a kind of shadow Labour party NEC, very similar to the strategy board of the Blairite faction Progress.

In one version of reality, Jon Lansman and his allies are saving Momentum from a delegate-based version of democracy in which far-left factions could seek to “capture” the organisation. This is a narrative that has been repeated by a hostile press with a sparse working knowledge of the left’s internal politics and an agenda that is well-served by exaggerating the role of Trotskyists in Labour and Momentum. But the largest Trotskyist organisation active in Momentum has only about 100 members. The force that Momentum’s leadership is attacking is a much broader layer of its grassroots activists who, like me, are shocked at its unwillingness to compromise.

This is happening because there is now a fundamental difference of opinion about what Momentum should be for. The new constitution – which was adopted by an email vote of a small committee in the space of an hour – is that of a disciplined, top-down organisation whose primary purpose is to mobilise its members inside the Labour party in support of Jeremy Corbyn. Although the new constitution was adopted on the premise of giving all members a say, members seeking, for instance, to propose campaigns or make internal rule changes, will have to collect thousands of signatures to call a referendum. They will then have to achieve a vote so large in that referendum as to make the task effectively impossible.

Supporting the Labour leadership is vital, but on its own it is inadequate. At the moment, some of the greatest minds of the British left are consumed by high-level chess games with the press and the parliamentary Labour party over Corbyn’s leadership. They are losing – because the left cannot win with clever footwork alone. Without a radical movement in society, Labour’s leadership will find itself pushed into performing the same kind of damaging compromise on principle – on freedom of movement of people, on economic policy – that is failing social democratic parties all over the western world.

In order for the Corbyn project to stand a chance at the ballot box, we need to shift the ground from under the Westminster bubble by fighting cuts with direct action, and convincing ordinary people of an alternative narrative about immigration and inequality. As the Tories lay waste to communities and services, Britain needs a movement of rebellion built on broad foundations, plugging Labour into social movements and giving social movements a voice in Labour. For that to work, we need empowered activists with a mind of their own – not just foot soldiers who cheer at the right time and vote the right way. Grassroots movements cannot flourish without internal democracy and political independence.

I cut my teeth during the student and anti-austerity movements of 2010 and 2011, explosive bottom-up revolts against neoliberalism that paved the way for the rise of Corbyn. If those movements taught me anything, it was that none of the established pillars of the left – not the organised far left, not the Labour left, not the trade union leaderships, not the NGOs and slick online campaign hubs – really had a serious strategy to beat the government. Corbynism’s claim to represent “a new kind of politics” is not just a slogan – it is also a statement of humility, an admission that we are looking for answers in a volatile new world.

The only force that can provide the inspiration, ideas and hard graft to carry Corbyn’s Labour into Downing Street is the grassroots of the Labour movement and a new wave of activists from communities and workplaces struggling for social justice. Momentum is a vital building block for that new mass politics – but only if remains united, and if it can combine its role in supporting Corbyn with a bottom-up democratic culture. For that to happen, its leaders must learn how to compromise.