CHEERING crowds flock to his rallies. Youngsters embrace him for selfies and hang on his every tweet. Jeremy Corbyn, improbable, crinkly rockstar of the far left, is on course to be re-elected Labour’s leader on September 24th in a landslide vote among the party’s members, hundreds of thousands of whom have joined up in the past year just to back him.

Yet Mr Corbyn’s popularity among Labour’s half-million members and affiliates is not replicated among Britain’s 45m voters, most of whom do not share his desire to overthrow capitalism and unilaterally forsake the country’s nuclear weapons, nor his soft spot for strongmen such as Vladimir Putin and the late Hugo Chávez. The party is polling at its lowest in opposition for 30 years. Among young people, his most sympathetic constituency, Mr Corbyn has an approval rating of -18%. Among the over-65s it is -68%. Labour is on course to lose scores of seats at the next election. And it will not end there. Parties often pick bad candidates—mainstream Republicans recoil at Donald Trump, for instance—but it usually costs them no more than one election. Mr Corbyn, by contrast, is packing Labour with allies and seems more concerned with building a long-term “movement” than winning power. The Conservative government can expect years without being seriously challenged in Westminster.

The story of how one of the most reliable vote-winning machines in the West drifted into irrelevance is a warning to parties everywhere (see Briefing). It is a tragedy for Labour, which under its recent centrist leaders was in power for 13 years, introducing reforms from a minimum wage to gay unions. And it is bad news for Britain. Experience, from Mexico to Japan, suggests the long-term absence of serious political opposition leads to bad government. Worse, Labour’s meltdown comes as Britain begins complex and perilous Brexit negotiations, which need scrutiny. What opposition there is will come from the Tories’ eccentric fringes and from the undemocratic House of Lords. And Scotland may wonder more than ever why it should remain attached to its Brexiteering big brother.

Left foot backward

Labour’s feebleness has already contributed to Britain’s most calamitous decision in a generation, that of leaving the EU. Although the party is pro-Europe, Mr Corbyn’s half-hearted campaign to Remain (he is a lifelong Eurosceptic who voted to leave in 1975) was one reason that the referendum slid in favour of Brexit. Since then, Labour’s leader has yet to ask a question about Brexit at his weekly grilling of the prime minister in Parliament. The shadow cabinet is so thin—three-quarters of Labour MPs have publicly called on their leader to quit—that the job of shadow Brexit secretary is being done part-time by the shadow foreign secretary. If the opposition did its job properly the government might be forced to come up with a Brexit plan that was halfway acceptable to the 48% who voted to stay. Instead it faces a louder and more serious threat from the more extreme Tory Brexiteers, who are urging an economically disastrous “hard Brexit”: leaving the single market entirely in order to impose controls on immigration.

The absence of an opposition will have an equally damaging effect on domestic policies. Theresa May, who became prime minister via a Tory leadership contest rather than a general election, is launching a prospectus unapproved by the electorate. She has set out a bold pitch to working-class voters who feel abandoned by Labour. This is welcome. Yet her proposals will suffer from lack of serious scrutiny. This week she announced plans to allow more state schools to select children based on ability, a laudable effort to help poor children but which could actually do the opposite (see article). For once, Mr Corbyn landed a few blows on her in Parliament. But the biggest push-back will come from backbench Tories; Labour is on its third shadow education secretary of the summer.

Perhaps the strongest brake on the government will be the House of Lords. The Conservatives have less than one-third of its members; contentious policies like the schools proposal are likely to run aground there even if they do not in the Commons. Yet the Lords—who are unelected, unrepresentative and include a bench of Church of England bishops—would provoke crisis if they went beyond their historical role of fine-tuning legislation to become a serious check on the government.

The zombie opposition

Labour’s malaise could even loosen the fraying union. Long allergic to the Tories and more recently out of love with Labour, Scotland has itself become something of a one-party state under the Scottish National Party (SNP). Mr Corbyn promised to win back Scotland by moving Labour leftward. Yet the Islington socialist is as unpopular there as he is in England. Scots now have little time for either of the parties that would rule them from Westminster. That may make independence (already back on the agenda following the vote for Brexit, which Scots opposed) more appealing. Brexit is also complicating relations with Northern Ireland, another place where Mr Corbyn—whose shadow chancellor, John McDonnell, praised the “bombs and bullets and sacrifice” of the Irish Republican Army in 2003—is not taken seriously.

In many democracies, parties come and go; there would be little to mourn if Labour were to wither and be replaced by others more in tune with voters. Under a proportional electoral system, Labour might shed seats to the leftish Liberal Democrats and the populist UK Independence Party. Moderate Labour MPs might even break away to form a rival outfit. Yet Britain’s first-past-the-post system makes it fiendishly hard for small parties to make headway. Labour’s crisis will therefore probably translate not into the birth of a bold new opposition movement but simply a Conservative landslide. Until Labour comes to its senses, those who oppose the government—particularly centrists and the 48% who voted to stay in the EU—will be poorly represented. Disaffection with the political process will fester. The witless Mr Corbyn was at least right when he promised his followers a “new kind of politics”. But a one-party state was probably not what they had in mind.

Correction (September 15th): An earlier version of this leader said that Mr Corbyn voted "against joining" the European Economic Community in 1975. In fact Britain had been a member since 1973; we should have said that in 1975 Mr Corbyn voted "to leave" it. Sorry.