JEREMY CORBYN’S hero is Salvador Allende. The Labour leader loves to recall his peregrinations in Chile in 1969 and 1970, when the left-winger swept to power on a wave of popular support. “I went on the May Day march in Santiago…and noticed something very different from anything I had experienced,” Mr Corbyn said in 2013. “What Popular Unity and Allende had done was weld together the folk tradition, the song tradition, the artistic tradition and the intellectual tradition.” The problem, he went on, was that the forces of the “deep state” (soldiers, spooks, tycoons) lived on nonetheless, so were able to depose Allende in 1973.

Corbynistas today fear their man will go the way of his hero: overthrown by his troops (Labour MPs, in his case) in a “coup” backed by shadowy business interests. As The Economist went to press they were closing in on the presidential palace: they just had to settle on a challenger, or a “Pinochet”, in the words of Paul Mason, an excitable pro-Corbyn commentator. Angela Eagle and Owen Smith, soft-left types who recently resigned from Labour’s shadow-ministerial line-up along with 63 of their colleagues, seemed the likeliest putsch leaders.

This showdown became near-inevitable last September, when Mr Corbyn won his party’s leadership thanks to a surge of new, left-wing members into the party. His formative trip to Chile explains why. It ignited his abiding enthusiasm for Latin American popular movements (he even speaks to his cat, El Gato, in Spanish). If he and his Mexican wife were to leave Britain, he says they might move to the Bolivia of Evo Morales, a leader of indigenous descent propelled to the presidency by Andean peasant farmers. Mr Corbyn is a longtime supporter of Hands Off Venezuela, a British outfit that lobbies for the ailing chavista regime.

Such movements epitomise Mr Corbyn’s democratic ideal. They consider themselves less election-fighting machines than revolutionary upswells; multitudes that primarily exercise power not through the legislature but through the charismatic influence of their leaders and by taking to the streets to give voice to popular anger. They seek to “prefigure”, or embody, a different sort of society by creating their own deliberative structures: from assemblies and single-issue campaigns to occupations and co-operatives. This style of politics is attractive to those on Labour’s left, like the current leader, who for decades have deemed their party’s boring “parliamentary road to socialism” inadequate, and its leadership hijacked by right-wing entryists such as Tony Blair. For them, MPs owe their first legitimacy not to voters but to the movement: to the members and the leader they have elected.

Hence the now-unfolding conflict. Over the ten months of his leadership Mr Corbyn has made only token efforts to render his party appealing to the electorate. His priority has been to coddle his left-wing activists: boosting their role in policymaking (through online polls, for example); telling them what they want to hear in his public pronouncements; sponsoring Momentum, a party-within-a-party that hassles and threatens moderate MPs with deselection; and offering an underwhelming reaction to the anti-Semitism infecting parts of Labour’s grassroots.

The last straw for many MPs was his half-hearted role in the anti-Brexit campaign. Some even accuse him of deliberately sabotaging it. Two days after the vote his shadow foreign secretary, Hilary Benn, told Mr Corbyn he had no faith in his leadership; Mr Corbyn sacked him, triggering waves of shadow-ministerial resignations and, on June 28th, a motion of no confidence in Labour’s leader that was supported by 172 of the party’s 230 MPs, many of them by no means Blairite. Since then Mr Corbyn has rejected successive entreaties to resign, reconstituted his shadow cabinet from the dregs of his parliamentary support and seized on the publication of the Chilcot inquiry into the Iraq war (which he opposed) to rally his supporters. The result is a giant rift in the party, with Mr Corbyn, some trade union leaders and most members on one side, and most MPs on the other. At the time of writing final attempts by Tom Watson, the deputy leader, to negotiate a compromise had come to nothing.

Always likely from the moment Labour’s members elected a chief so dismissive of his MPs and their mandates, a split now looms. If a moderate takes on Mr Corbyn in a leadership contest and wins, there is talk of Unite, Britain’s largest union, whose bosses are close to Labour’s left, underwriting a new party formed of loyalist MPs and Momentum. More likely, the moderate candidate will lose. Polls of Labour’s members show that, although Mr Corbyn lost support during the referendum campaign, he would still beat Ms Eagle, his most popular prospective challenger. If he clings on, or one of his allies runs in his place and wins, some moderate MPs plan to declare independence. They might forfeit the party’s infrastructure, but would not struggle to find funding and, if larger in number than the rump Parliamentary Labour Party, could form the official opposition.

Both sides are tooling up. Moderates are taking legal advice about who would keep Labour’s name, logo and assets following a split. Recruitment drives by both sides have increased Labour’s membership by 100,000, or about one-quarter, since June 23rd.

Viva la revolución

The coming months will be ugly. They may culminate in centrist MPs abandoning a party that has abandoned them, and at a time when Britain needs a strong, united opposition. Still, the confrontation is welcome. Labour has long been an awkward coalition of anticapitalists and social democrats, undermining and frustrating each other. With the Tories drifting rightward and the centre ground looking sparse, Britain could use a centre-left party capable of holding the government to account and, as Brexit negotiations begin, pressing it to keep the country as open and dynamic as possible. Whether by defeating Mr Corbyn or splintering off, Labour’s moderates now have a chance to create such a force.