Calamity, cataclysm, catastrophe: the lexicon ran out of words for Labour’s plight. Keir Starmer’s career-saving “reset” needed to be monumental. It was … OK-ish. But it didn’t dispel the sense of a country with no overall control. As ever, his tacking neither right or left, as he wrote in the Guardian, sends many Labour people into paroxysms of despair, when last week it lost most votes leftwards.

Britain at the heart of Europe was absolutely the right message, “shoulder to shoulder with the countries that share our interests, our values and our enemies” on growth, defence and energy. But as Starmer said himself, “incremental change won’t cut it”. His message lacked the ear-splitting sounds of red lines snapping and a manifesto straitjacket bursting open. Tiptoeing towards the single market and customs unions for a manifesto three years away doesn’t cut the mustard. What voters sniff, remainers and leavers alike, is the odour of cowardice, an unwillingness to say what he and Labour undoubtedly feel about Europe – rejoin ASAP.

Brussels has much to fear from these election results. Nigel Farage threatens the future of any negotiations to rejoin. Starmer said Farage and the Conservatives are defined by breaking our relationship with Europe. Quite right, and it’s for Labour and pro-EU parties to brand them indelibly with the lies they told and the lethal damage their Brexit did.

The alarm sounded last week, less for Labour’s future than the country’s at large. The hard right won, the progressives lost. Reform UK and Conservatives scored 47%, while Greens, Labour and Liberal Democrats scored 43%. Farage, rightly labelled a “grifter” and “chancer” by Starmer, would almost certainly be prime minister on those results. I fear the Tories in their modern Brexit incarnation would rather share power with these Trumpites than join the resistance. Look how their Telegraph and Mail organs ooze with favourable Farage coverage.

A Reform government is a truly terrifying prospect: Starmer warns of “very dangerous opponents”. Beware those who now normalise Reform as just a party like any other. The charge against Reform is Trumpism, a populism that feeds off the discontents of the left-behind, but only benefits the party itself and its handful of multibillionaire benefactors. The UK’s non-constitution with vast Henry VIII powers would give Farage fewer checks and balances than Trump. His attempt to justify a £5m personal gift suggests this could lead to kleptocracy. Farage is no stranger to dodgy schemes: see the nonchalant investment of £215,000 in Kwasi Kwarteng’s crypto enterprise and cash side-hustles once unthinkable in a serious contender for No 10. There are no guardrails.

Across Europe, populists scapegoat immigrants as the cause of all social ills, rousing poisonous hate as cover for their cuts. Hope Not Hate uncovers repellent racism among their candidates: that’s not new, but the difference is that Reform’s deputy leader, Richard Tice, on the BBC refused to condemn a Reform councillor joking about melting Nigerians into potholes, ground no elected party would have tread even a few years ago. Later the party had to back down, placing the councillor in question under investigation.

Here, as across Europe, the battle against Trumpism is by far the greatest political threat of my lifetime. Boris Johnson and Liz Truss were a first taste, but a Farage win would be of yet another order.

Labour has to keep its attention fixed on that. Starmer must take his own words to heart and ensure he doesn’t end up assisting Reform by staying on too long and shunning alliances with other parties in the face of danger. Conservatives of a better era would be allies too, but the party’s current iteration risks choosing to be consumed in a pact with Farage, rather than join the anti-Trumpite alliance. This is Labour and the left’s single mission: snuff out these sparks before they burn down Westminster. Bizarrely, Starmer kept referring to Reform and Green threats as if equivalents. That is frivolous when faced with a threat such as Farage.

Suggesting Labour faces anything less than extinction risks sounding like the Black Knight’s limbless torso from Monty Python and the Holy Grail hopping about still challenging: “’tis but a scratch”, “just a flesh wound”. But Labour may not yet be a dead parrot if it makes the right choices.

Hatred of Starmer (puzzling to me and many) runs deep at -69% disapproval (just 24% approval), according to YouGov. But loathing of Farage is powerful too, at -65% (27% approval). Reform has slipped 4% in the polls from last year’s May high point: that’s beatable, but probably not by Starmer.

Who by? Andy Burnham is the only contender with positive polling. It was deeply dishonest of Starmer to say it was up to Labour’s national executive committee (NEC) to decide whether to bar Burnham again: Starmer can influence the majority of NEC votes. Lavishing praise on Burnham’s Manchester work is bogus politics: he should at least say what he means. To block the likeliest brake on Farage is not taking that threat as seriously as he pretends.

The national mood may be general disgust with politicians, but someone has to win the next election. In three years’ time Labour’s candidate could be the least improbable. That depends on progressives uniting – just enough – in a mission to send Farage’s Trumpist challenge back to the sinkhole it came from.

• Polly Toynbee is a Guardian columnist