Of all the endings possible in the Brexit drama I can now see only two. In the first, Boris Johnson takes control of the Conservative Party, commits it to a No Deal exit from the European Union on 31 October and achieves that aim.

Then, in a snap election, Johnson manages to destroy the Brexit Party, who win only where local Tory associations have stuck with their liberal/Remain candidates. He then does a Canada-style free trade agreement, albeit amid economic chaos, and to Britain’s permanent disadvantage. The prize, for the coalition of xenophobes, misogynists and free-marketeers he will assemble, is Trumpian chaos for the foreseeable future.

In the second scenario, Labour jerks awake from the strategy of triangulation and apathy and starts to fight with the kind of passion and principle currently being shown by left MEP candidates like Laura Parker and Eloise Todd, and the frontbencher Clive Lewis MP.

In this scenario, Labour makes a hegemonic offer to the progressive majority in British society: give us your votes to stop this madness. Simultaneously it uses its radical economic platform to reach across the Remain/Leave divide in small-town working class communities. It begins using language that mobilises working class progressives, like those who chased Tommy Robinson out of Bootle to defeat Farage, UKIP and the fascists in their communities.

In both scenarios, the second referendum will become less important than manifestos and narratives of political parties in a general election. Let me explain how it happens.

On Sunday night, the Brexit Party looks set to win the EP election on around 30 per cent; the unequivocal pro-Remain parties will form the numerical majority; the Conservatives will be crushed; and the Tory civil war will begins.

Next, Johnson stages a right-wing nationalist leadership bid for the Conservatives. It is worth remembering that before Farage launched his party, and before May said she would quit, Johnson was said to in exploratory talks with both Farage and Bannon about the formation of a new right wing force.

A source close to Farage told me before its launch that TBP was never conceived as a long-term project, only a tool to bounce the Tories into the required posture. If Johnson wins the leadership election on an outright pledge of No Deal on 31 October, he does not need any other electoral mandate to make it happen. Only a parliamentary majority to revoke Article 50 can stop it.

As a perpetual chancer, Johnson might be tempted to use the Tory conference as a platform for a three week snap election campaign culminating on 24 October, calculating that a Tory victory would force the EU to extend the leaving date and revise the Withdrawal Agreement. But the safer course, politically, would be simply to let a “managed No Deal” emerge out of the political stasis at Westminster. The executive would have statute on its side. And the political elites of Germany and France – who will see a Johnson-led Britain as so much dirt on the shoes of Europe – would happily see Britain leave without a deal and implode.

After that, we get the long-predicted Brexit chaos, though probably softened by emergency monetary and fiscal stimulus. But as with Trump, the faction of the financial and property elite that would back Johnson revel in chaos. Murdoch, the Barclays and – because it’s good for business – the Harmsworths and Reach plc would all pile their right wing newspapers in behind the call for a “strong man prepared to break the rules” to end the chaos, and this would turn out to be none other than the man who had caused it.

Now let’s outline what could stop this happening.

The first hurdle is May’s new attempt to get a revised Withdrawal Bill through parliament. The document that the Tories leaked to the press on the day Labour quit the talks was, I am told, a fiction. Nobody seriously contemplated Labour acting as a virtual Coalition government to get it through.

Nevertheless that document will likely form a template for May’s offer, aimed at getting between 25 and 40 members of the Parliamentary Labour Party to defy the whip. Some of them are devout economic nationalists; some on principle want to deliver the outcome of the 2016 referendum at any cost; a few are just unprincipled people of the kind we need to remove from Labour politics.

Defeating May’s bill should, in the end, be possible because a much wider group of right wing Tories, beyond the ERG, now sees the possibility of electoral oblivion if the Brexit Party steals their mass base.

But whipping against the revised Withdrawal Bill will also be a moment of truth for those on the Labour left who have, since December, revealed themselves as closet Lexiteers. Here’s why.

Once May’s Bill is defeated, and she is gone, the only possible form Brexit can take is harder. The political space Corbyn has been prepared to share with May – the search for a soft Brexit with a customs union and single market alignment – will disappear. The brutal game of political reality leaves room for only hard Brexit or Remain.

It is the dawning realisation of this that makes me fear a bigger pro-Brexit rebellion inside the PLP in two weeks’ time. However, the forces of the internationalist left inside Labour are mobilised and (after the doorstep experience) angry, and should be enough to see any rebellion off.

But what then for Labour? There is, right now, an implicit strategy being followed by Labour HQ and some in Corbyn’s inner circle: to sacrifice the 23 May election for the greater good of winning a subsequent general election, with both Leave and Remain votes.

At one level it makes sense. In a first-past-the-post system, facing the possibility of Johnson in power for five years, there are reasons to believe Green, CUK and LibDem voters might once again lend Labour their votes in a general election. To convince yourself that voting Corbyn was “just the same” as letting Saint Boris of the Watercannon run Britain would take a particular form of nihilism.

The problem is that, as May’s Brexit deal unravelled and the Brexit Party sprang from nowhere, large parts of progressive Britain began to understand they are in an unavoidable culture war. The right has a story: a culturally exclusionist, white, nostalgic vision of Britain as the airstrip for Trump, Pompeo and Bolton’s neo-imperial aggression. The progressive majority needs a better story than soft Brexit.

It made me cringe to see self-proclaimed Corbynistas trumpeting a Survation opinion poll predicting that, because of the rise of the Brexit Party, Labour would gain a 28 seat Commons majority with just 32 per cent of the popular vote.

First, because Corbyn’s failure to back the reform of MP selection procedures means that a radical left manifesto would be a hostage to the Labour right in such a situation. The centre and right of the PLP showed in 2016 how easily they can combine when it comes to destroying or neutering Corbynism.

Second, because an election victory gained simply by splitting a much bigger right wing nationalist vote between the Tories and the Brexit Party would arm the latter to foment extra-parliamentary resistance, abetted by the money of the American alt-right and the thugs of the Tommy Robinson movement.

But third, and most importantly, because it is evidence that a nostalgic segment of the Labour left just does not understand what kind of world we are living in.

They interpreted Labour’s 2017 result entirely as a function of Corbyn’s popularity – not the clear tactical voting revealed by subsequent analysis. Now they are refusing to see the emergence of a major cultural conflict: a situation where, whatever the left offers in terms of economic or social reforms, the progressive half of the electorate increasingly defines itself against Brexit, which is a cypher for all the other reactionary projects of the right.

Corbyn is right to say only Labour can unite parts of the Leave and Remain voting sections of the population – but the question is on what?

There has to be a common story. To people who hate gay marriage and want to ban halal food, Labour can offer nothing. But it can offer – even in the most fractured, Leave voting communities – a narrative of hope based around secure employment, massive investment in public services and the promise to crack down on the petty violence, anti-social behaviour and organised crime that plague its traditional voters.

The premise for the conversation is to be clear on where Labour stands on Europe. It’s true that in some Northern ex-industrial communities there is antipathy to the second referendum – who wants to spend another six months in a slanging match with local fascists and racists? But it is not true, as Lisa Nandy MP claims, that this is representative of the wider British working class.

The real working class is multi-ethnic, lives in cities as well as towns, and is to be seen just as much as at events like Parklife as the Durham Miner’s Gala. In the minds of those fighting hardest to revoke Labour’s commitment to a second referendum, it seems that there is an unspoken hierarchy, in which Britain’s 320,000 nurses, 20,000 of whom have no vote or British nationality, are somehow “less working class” than pensioners from English midlands who refused to support the miner’s strike.

Thankfully the argument over the referendum soon won’t matter. Once May’s deal is defeated, all possibility of a second referendum on a given deal recedes. Instead, the issue will be decided at a general election in a straight fight between hard Brexit and Remain – or, if the election is held subsequent to a No Deal Brexit, simply between xenophobia and tolerance.

If Labour wants to win the coming snap general election, its leaders must build their bridges back to those voting tactically for the Greens, Libdems, SNP and Plaid this week.

As you watch the reactions to the results next Sunday, listen out for any politician who says the projected mass desertion of Labour by progressive voters is either “irrelevant” or “self-indulgent”.

I’ve learned through bitter experience that this is the talk of people who prefer glorious defeat over victory and the compromises needed to achieve it.