Perhaps the only success of David Cameron’s reckless EU referendum gamble was that it took the Tories’ toxic split on Europe and shared it with the rest of the country. At least they are no longer the laughing stock: now we all are.

Yet among the cluster of possible solutions around Norway this or Canada that, or a customs union of sorts, the danger remains that the bigger picture is being missed: the political effect of Brexit on the UK and our foreign relations. Brexit is one part of a project to reshape the politics of the west and set it in concrete. And too many on the left are happy to sleepwalk into that oblivion.

There is no justification on the left for Brexit. That so-called “lexiteers” are still invoking Tony Benn in their justification for a left Brexit demonstrates how out of touch they are with the modern struggles we face. I recall the dark days of Thatcherism when it was often only European law that prevented deeper Tory attacks on environmental and workplace protection, and that was before my colleague Jack Dromey, then a union official, led the Bournemouth bin workers to a famous victory to protect their terms and conditions when facing privatisation, a victory only possible because of European law.

But even since then the world has moved on, and however damaging globalisation has been, it can now only be tackled on a global scale. Britain standing alone cannot face down the forces of global capitalism. And the Brexiteers know this, which is why they are doing what they are.

After 29 March, the Brexit extremists will no longer have the restraining influence of the EU to hold them back

For these Brexit extremists, this project is about aligning the UK with the Trumpist US. The Trumpeteers and the Brexiteers are the same people, on different sides of the Atlantic. Whether from the Ukip tendency of Nigel Farage and Arron Banks, or the Conservative strand of Michael Gove, Liam Fox or David Davis (the latest senior Tory to visit at the behest of that shady nexus of so-called thinktanks linked across the Atlantic), the aim is the same.

They want to take the UK out of the EU and join us instead to the North American Free Trade Agreement (Nafta) or the Pacific Alliance, offering free trade with these countries but none of the environmental, labour or consumer protection offered by the EU.

This unrelenting ideological approach was summed up by one Brexiteer Tory in a meeting I chaired in the Commons for aerospace and aviation businesses. These companies were calling for some regulatory certainty so they could at least keep building or flying their aircraft after 29 March. My Brexiteer colleague announced that we could achieve regulatory alignment easily, by aligning instead with the rules and regulations of the Federal Aviation Administration of the United States.

The Brexiteers know that the UK cannot survive on its own. The romantic notion of the UK as a freestanding global trading nation is a myth designed to hoodwink the public with a fairy story. There are only two options globally: the EU or the US, and despite the obvious geographical problem, these extremists want to tie the UK to Trump’s US.

At the top of the Labour party, Keir Starmer’s forensic approach in opposing the government has been outstanding. Yet politically, elsewhere, too often Labour colleagues’ responses have been weak, flaccid and fearful. Aside from the few deluded and outdated lexiteers, too many colleagues still refuse to see this for the ideological battle it is – and are willing to accept the result of the flawed and dodgy referendum as the path of least resistance.

We know the Brexit extremists won’t stop after 29 March: they will never be satisfied and they will no longer have the restraining influence of the EU to hold them back. Brexit is just the beginning. Yet Labour MPs acquiesce to Brexit, for fear of upsetting the millions of Labour voters who voted leave for so many different reasons.

Some of those leave voters will have been anti-European, for sure. But many were sick of austerity, failing public services, insecurity at work and a lack of affordable housing, and fell for the con that it was all because of immigrants, or the EU, or both. Some just wanted to vote against something, anything, to protest at how bad their lives were. And twice I was told by voters that they were voting leave because they didn’t like Cameron.

Aside from those who wanted to see the back of our former prime minister, it is clear that those voters will be sorely disappointed by Brexit: none of these ills will be cured by leaving the EU. There never was going to be £350m a week extra for the NHS, and the economic crash after we leave the EU will mean there will be no money available to renew public services. And when medicines become unavailable and motorways turn into lorry parks, and when family holidays to the Med become unaffordable due to visa costs and a plummeting pound, they will blame us for failing to stop this mess.

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Some fellow MPs are fearful of the social chaos a further referendum may bring about. Well, that chaos was already unleashed in 2016. The far right is already a threat and will feel more empowered post-Brexit. That is a fight we will have to have anyway, as John McDonnell has identified. And we never defeated the far right before by ceding ground and saying, “Oh, go on then.”

If Brexit was wrong in June 2016, then it is wrong in January 2019, just with more proof. But more than that, it is the generational opportunity the right in the UK has seized to stage what is in effect a rightwing coup: to finally remove all vestiges of the postwar liberal consensus, and paint on the remaining blank canvas the bleakest, nastiest picture of the UK possible.

Those of us on the left still have the chance to stop this hard rightwing coup. But we need to look forward, not back, and we must be as bold in stating our values of fairness, decency and internationalism as the right has been in forcing through their bleak and divisive agenda. And above all we must be bold enough to call Brexit out for what it is, and to fight to stop it. Acquiescence is no longer an option. If that requires supporting a people’s vote on the final deal with an option to remain, then so be it.

• Chris Matheson is Labour MP for City of Chester