History is offering Jeremy Corbyn the gift of his dreams, and he is rejecting it. He has said he will do everything necessary to save Britain from the bizarre self-harm of no-deal Brexit, personally crafted by Boris Johnson. He will not.

Corbyn will not lay aside partisan rhetoric and muster the parliamentary coalition that alone might bar no deal in the coming weeks, nor will he give way to other potential and less abrasive leaders of such a coalition. Every word Corbyn utters makes it ever more impossible for Liberal Democrats, nationalists or dissident Tories to lend him support, however temporary. Corbyn does not want to stop Brexit. He just wants a general election.

In today’s speech, the Labour leader should have presented himself as the voice of majoritarian sanity. He should have sought to muster the diverse tribes of political Britain to an emergency, to expose Johnson’s no-dealers as a masochistic minority. He should be reaching out to all Johnson’s opponents, talking, cajoling, compromising, fashioning the lowest common denominator of consensus. Corbyn should be the magnetic attractor of the “will of parliament”. As such, he would deserve the nation’s thanks for saving it from the disruption, hardship and expense of no deal – and for honouring the “frictionless border” that the Brexiters promised. Instead, he is simply aping Johnson. He is defaulting to the occupational disease of British politics – that it is about fighting elections, not governing countries.

The Labour leader should recognise that he is in large part responsible for this crisis, by refusing to support Theresa May’s sensible withdrawal agreement. He voted against it even when such a vote was certain to lead to precisely the no deal he now claims to oppose. His motive then was not the national interest but to bring down May. He succeeded.

Time has moved on. May’s agreement is still on the table, enabling a British departure from the EU on 31 October – in accordance with the 2016 referendum – while keeping the UK within Europe’s common economic area pending a final settlement. Any issues in such a settlement would be settled in the transitional period. Under the deal, both sides would live to fight another day.

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Despite the current noise, the sticking point to the May plan remains the Irish backstop. It is at least conceivable that its open-endedness might be negotiable with the EU – that is time-limited. But any such concession from the EU is implausible unless backed not just by the Irish but by a stable body of support within the British parliament. That support would require a leader and, for the time being, disciplined followers.

Neither Johnson nor Corbyn can offer such leadership. Johnson does not care. Corbyn merely wants Labour to win an election. To that end, his best hope is surely now to behave like the saviour of a nation in distress.

• Simon Jenkins is a Guardian columnist