Friends don’t let friends go Brexiting without a mandate. But where are Theresa May’s friends? The prime minister staggers towards negotiations with the European Union like a drunkard crossing a car park – bold pace, wobbly gait. She is in no political condition to get behind the wheel. This is when partners are meant to intervene.

Talks are due to begin in Brussels next week. If that date has come around too fast for the prime minister’s comfort, it might be because nine weeks of the available preparation period was squandered in an election campaign that was meant to inflate her personal authority, but instead punctured it beyond repair. May’s eagerness to get on with Brexit is also a reason to disqualify her from the task. She is up against a tricky deadline because her judgment and grip are unsound.

The missteps began at the Conservative conference last October. The prime minister, new to the job and unelected, cast herself as the incarnation of a romantic national spirit of Brexit. In her haste to expunge any remnant of remain from her person, May locked Britain on to a course of severe rupture: out of the single market, out of the customs union, and beyond the jurisdiction of the European court of justice.

There is a zealous breed of Eurosceptic that sees any compromise on those points as a synthetic Brexit, unworthy of the name. But that was not the view taken by most leavers during the referendum campaign. The more common position was the one cultivated by Boris Johnson – blithe pretence that economic benefits of EU membership would still be available; that a cost incurred by departure was really a prize; that the cake could be had, eaten and given to the NHS all at once.

May’s task was to explain to the British public that this option did not exist, but she ducked the challenge. Instead she concocted a hard and impenetrable Brexit line in exclusive conclave with her chiefs of staff, Nick Timothy and Fiona Hill (both defenestrated in a post-election reckoning). The Treasury was not consulted. EU leaders were not forewarned. They have taken May at her word, and are now ready to negotiate on the assumption that the UK is still wedded to the wild course of action advertised by its prime minister last autumn. A hung parliament suggests that the UK is not.

In a less polarised climate, the obvious thing for May to do now would be to reach across party lines and calibrate a consensus position. Senior Tories are urging her to do just that. But British politics does not lend itself to that kind of bipartisanship, and Labour has few incentives to be magnanimous to a debilitated Tory leader who has just spent two months depicting Jeremy Corbyn as a menace to civilisation.

Besides, Labour has benefited from studied avoidance of Brexit detail. This was one of many areas where Corbyn’s capabilities were misjudged by his critics. Before the general election, it looked as though his acquiescence to article 50 would alienate remainers without seducing leavers. Instead, he avoided meltdown in areas where the appetite for Brexit was strong, while persuading anxious pro-Europeans that he shared their emotional recoil from May’s nationalistic culture-warrior alignment with Ukippery.

Corbyn’s ambiguous position on Europe looms large in the interrogation of my own failure to anticipate his strong campaign performance. Labour has become the repository for hopes that May’s brand of Brexit can be removed from the shelves, but the party’s manifesto commits to quitting the EU on terms scarcely less severe. Meanwhile, the Conservative position is spongier than it seems. The small print recognises the need for “phased implementation”, which amounts to tacit recognition that the two-year article 50 countdown isn’t long enough to settle future terms of commerce. Some transitional zone between full membership and going it alone is unavoidable.

‘A space is now available where emboldened Labour MPs and their chastened Tory counterparts can collaborate on proposals that look more like Norwegian and Swiss variants of EU-integrated non-membership.’

In theory, a space is now available where emboldened Labour MPs and their chastened Tory counterparts can collaborate on proposals that look more like Norwegian and Swiss variants of EU-integrated non-membership. Some leavers used to be sanguine about that model, but went off it as soon as remainers adopted it as their desultory Brexit-lite option.

The case for any kind of semi-detached compromise is politically awkward for leavers. It smuggles in recognition that Britain’s interests are served by intimacy with the giant trading bloc on its doorstep. But then it would be madness to surrender a seat at the table where the terms of trade are settled. The logic of less Brexit being good is that no Brexit is even better.

Yet over 80% of voters have just supported parties promising a journey in the opposite direction. The election affirmed Brexit while revoking the prime minister’s licence to carry it through. The UK is getting good at ballot-box consultations that are meant to settle European matters but fail, channelling different grievances instead.

The proposition that Brexit shouldn’t be done is buried two ballots deep. Can it be excavated?

Two in as many years. The winning side in the referendum still hasn’t explained how any of the social, economic and cultural frustrations that fuelled support for the leave campaign are practically resolved by terminating EU membership. The past nine weeks should have been May’s opportunity to fill in the blanks. She couldn’t. She doesn’t know how.

Brexit presents any government with an absurdly paradoxical instruction: restore national confidence and financial security by means that diminish the country and destabilise the economy. It can’t be done. Yet the proposition that it shouldn’t be done is now buried two ballots deep. Can it be excavated? It doesn’t look likely, although I’ve learned not to rule anything out these days. And if I have to eat words, none would go down with more relish than my gloomy assertion in March that May’s article 50 letter was the irrevocable death warrant for Britain’s place in the European project.

But for now the task is not yearning for an improbable reprieve. It is averting an imminent calamity: the prime minister’s embarkation on separation talks without a mandate, a strategy or a parliamentary majority, fuelled only by a skinful of Brexit-means-Brexit moonshine.

Hand over the keys, Mrs May. You’ve had enough.