Jeremy Corbyn’s supporters are in full ‘optimism of the will’ mode. And rightly so. The cynicism with which the election was called has been met with an exhilarating display of what belief in a political project looks like. After decades of democratic anaemia, dwindling party affiliation, and electorates holding their noses and voting for the least worst option, what we are seeing here is a crashing return of principles and convictions into the political sphere.

On current predictions, Corbyn’s campaign performance has reversed a year of terrible polling, and his radical left manifesto may be about to get more votes than the nervous compromises and short-termism the Labour establishment has until recently been addicted to – perhaps even more than Tony Blair won with in 2005.

But we need to be anticipating the worst too. Even if this week’s surprise polling has put the party thrillingly close to power, the left needs to be preparing for the long-expected eventuality that the party will suffer badly in terms of share of seats. In England they are up against a historic consummation of two strands of conservatism that is going to take much longer to disentangle. Ukip’s support was absorbed wholesale by Theresa May’s commitment to hard Brexit and attendant cultural conservatism. Meanwhile, the socially liberal Tories won to the party by David Cameron, who wouldn’t have been seen dead with such a prospectus in the 2000s, have found themselves rather relaxed about it now.

It’s hard to see what incarnation of Labour could win under these circumstances. But Labour’s loss of this election will be blamed on Corbyn all the same, and he is going to face enormous pressure to resign.

#KeepCorbyn?

Why would Corbyn’s supporters continue to back him even if he loses the election? The problem for the left in addressing Corbyn’s poor personal popularity has all along been the lack of natural legacy candidates. The demoralizing of the Labour left in the 1990s and 2000s, and its small recovery during Miliband’s tenure, has given a strange shape to its presence in the party: the prominent left MPs are all either veteran backbenchers in their sixties (Corbyn, McDonnell, Abbott), or the intake of 2015 MPs in their thirties (Rayner, Long-Bailey, Burgon, Smith) and forties (Lewis, Butler, Osamor), without experience or institutional foothold in the party.

This is why, when, after the EU referendum, the parliamentary Labour party (PLP) saw its chance to oust Corbyn, their ‘chicken coup’ was met with a completely unanticipated kind of resistance. As Richard Seymour reminds us, “the Tom Watson magic that worked on Blair and forced his graceless resignation did not work on Corbyn”, and in the face of the combined might of polite opinion, the media, the PLP, every living former leader, and all conventional rules of what is reasonable, Corbyn adopted the heroic bêtise of simply staying put.

In one of a number of ways, the ‘chicken coup’ inadvertently strengthened Corbyn’s hand. The mass resignation of shadow cabinet members at its start meant these mainly soft left MPs could be replaced with the young Corbyn allies of the 2015 intake, which has now given them a year of experience at the head of the party. Under ordinary circumstances, the elevation of any of them to the leadership would still be premature. But there are impressive media performers among them, and whoever it is would come to the post without the baggage of controversy that decades on the battlegrounds of the left has given a Corbyn or a McDonnell.

If Corbyn is to stand down, it should only be on condition that one of these young successors can be assured a place in a leadership contest to replace him, allowing the membership the opportunity to give a mandate to an anti-austerity program once again. Given that under current circumstances, none of the prospective candidates are likely to be able to secure enough nominations within the PLP to enter the contest, however, there are only three main ways in which this could be brought about.

1. The party strikes a deal.

The most amicable version of a transition from Corbyn in June would be the PLP committing to lending a Corbyn ally the requisite nominations to enter a post-Corbyn leadership contest – the logic being that they would prefer to take their chances with a Clive Lewis or an Angela Rayner to being beaten by Corbyn yet again. Without such an offer, Corbyn will no doubt remain in post until the party conference in September, with the aim of effecting…

2. The McDonnell amendment.

The ‘McDonnell Amendment’ is a measure to reduce the number of nominations a candidate requires in order to stand in a Labour leadership election from 15 to 5% of MPs and MEPs. The left does not currently hold the support of enough of this gatekeeper caste to get a candidate on the ballot, and Corbyn only got a place in the 2015 leadership election because MPs complacently lent him their nominations to ‘widen the debate’. Without a deal of the kind described above or a reduction in the number of nominations required, Corbyn’s resignation would mean the end of the left ascendency in the party.

Of the three eventualities, the passing of the McDonnell Amendment is the one Corbyn supporters have the most agency over. As well as 50% of trade unions, 50% of CLP delegates at the Labour conference must vote for the measure, and these delegates are being decided by ordinary members within their CLPs right now, with 23 June as the deadline. Who individual members vote to send to conference to vote on the amendment will be a deciding factor in whether Labour continues to be led from the left after Corbyn.

3. Labour’s losses favour the left internally.

There have been several interpretations of the likely effect of dramatic seat losses on the ideological makeup of the Labour party. It would be foolish to be over-dependent on these predictions, but it does seem that among those Labour MPs with small majorities in hostile seats are several prominent critics of Corbyn, and that many key Corbyn allies are placed – or are being placed – in comparatively safe seats. No one from the Labour left should relish such a perverse incentive. But if this does play out, then the existing nominations for a Corbyn successor within the PLP may be magnified even without the McDonnell Amendment, simply because 15% of a smaller PLP will be more easily reached, and by a Labour left more proportionately powerful.

Lacking any of these eventualities, the likelihood is that Corbyn will continue, and the membership must be rallied to back him again. If May gets the mandate she is seeking, Britain will be on course for yet more insecurity of working conditions, an ongoing rise of in-work poverty, and a revanchist racism cultivated at the top of government itself.

It was Labour’s inability to differentiate itself decisively from these tendencies in the last incarnation of the Tory party that led Labour members to support Corbyn in the first place. Yet the recent briefing from an anonymous moderate dismissing the Labour manifesto’s “freebies […] for the feckless poor” is symptomatic of a party machine that still just doesn’t get it. The Labour manifesto is important not only because it has proven that radical leftist proposals can be credible and popular today. More significant is the overdue defiance it offers to the failed free market consensus, and its concomitant rehabilitation of the kind of dynamic state we are going to need as we anticipate, for instance, a future of increased automation and the uberisation of the labour market.

Nobody voted for Corbyn thinking a left transformation of the party would be complete and electable within two years. The current polling is an impressive achievement, but this election is not our test and it is not our timetable. Voting for Corbyn’s leadership always meant consenting to do the slower work of making Labour into a party capable of making the case for an interventionist state, which is the only alternative to the death-driven orthodoxies of these fag ends of neoliberalism. Our work is not done. And on 9 June we will take it up again.