Party democracy is the enemy of representative democracy. Party democracy stops MPs speaking out against racism and warning of the perils facing their country. Party democracy makes politicians put their members ahead of their constituents. Party democracy makes them flatter coteries of arrogant obsessives. Party democracy is the enemy of conscience and judgment. To borrow a phrase, the party has become the enemy of the people.

Who does your MP represent? Who are they frightened of? You and your neighbours? What creaking haycart brought you and the rest of your yokel friends into town? “Control of politics has passed to unelected and irresponsible members,” says the historian Robert Saunders, one of the best analysts of British democracy’s decay. “Boris Johnson or Jeremy Hunt needs the support of about 70,000-80,000 Tory members to become prime minister. That’s roughly the size of one parliamentary constituency.”

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Saunders is shocked that hardly anyone seems to grasp that the next prime minister will be the first to take power without any kind of democratic mandate, however tenuous. Many prime ministers have gone to Downing Street without holding a general election. But they were chosen by MPs, who were elected by, and accountable to, their constituents. Labour party members might have chosen the successor to Tony Blair and Tory members the successor to David Cameron. As it was, Gordon Brown and Theresa May were returned unopposed.

We have had to wait until 2019 for our anti-democratic counter-revolution. Only now will we have a PM chosen by members who are overwhelmingly white, southern, old and wealthy, as everyone says, but also extraordinarily conceited, a point I could do with hearing more often. They don’t want to know that May’s withdrawal agreement can be prettified but not fundamentally altered. Nor will they tolerate warnings about the dangers of no deal. No one who has followed Boris Johnson’s career will be surprised by his willingness to please his audience: cowardice defines him. But Jeremy Hunt does not dare tell hard truths either, because he knows they will lead him to certain defeat. To make the point better than I can, 36,000 people have joined the Conservatives recently to claim the right to choose “your” new prime minister, a right that you will be denied. Why are we not enraged by this rigging of the system?

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Because the next PM will have no electoral mandate and no workable majority, prime minister Johnson, and I fear we must get used to those words, is considering closing parliament to force through a no-deal Brexit. The Brexit referendum did not include no deal on the ballot paper. The Commons is against it and he does not have the authority of a successful election campaign to justify it. Johnson’s sole mandate for shuttering national democracy is the vote of Tory members. This is the “democracy” of a members-only golf club, not of a free country.

The far left showed the way for the Brexit right. In 2016, Labour MPs, who represented millions of Labour voters, told Jeremy Corbyn to go by 172 votes to 40. Labour members overruled them. I thought at the time how absurd it was for far-left propagandists to talk of a “coup” – as if Labour MPs were Pinochet’s troops storming the leader of the opposition’s office. In retrospect, it appears sinister: the more so as Corbyn and his aide Seumas Milne are now inciting party members to frighten MPs into silence.

If Panorama had aired whistleblowers from a corporation, describing how they had been undermined, bullied and forced out of their jobs, had breakdowns and contemplated suicide, for the “crime” of investigating institutional racism, the chief executive would have been forced for the sake of appearances to promise to mend his ways. Corbyn unleashed his “outriders” instead: supposed journalists who owe their loyalty to the Labour party press office rather than their readers and editors.

Jews took the viciousness as Labour’s licence to racists to carry on as before. If you are an antisemite, you can now dismiss your accusers in Labour’s words for their “personal and political hostility to Jeremy Corbyn’s politics”. MPs saw something else, and it scared them. They saw the Twitter mobs and Momentum urging members to deselect them, and learned that the safest course was to shut up. Neil Coyle, one of the Labour MPs who will speak out, and you will notice it is always the same Labour MPs who speak out, said the outriders were Corbyn’s equivalent of Mao’s Red Guard.

Party democracy in Labour allows the leader to keep his MPs in line by denouncing and humiliating Labour’s “capitalist roaders”. Threats to deselect Conservative “traitors” who oppose a hard Brexit are a means of forcing Faragism on the Tories. Before you write to complain, I accept that not every Labour and Conservative member is a thug, fool, antisemite or Islamophobe, but their ugliness or lack of it is irrelevant.

We are a democracy and power should flow from the people, not from a privileged caste in a private club. Saunders says that either we return to MPs choosing leaders, accept that no one can become prime minister without first holding an election, or move to a presidential system. Democrats and Republican supporters, after all, have the right to choose presidential and vice-presidential candidates before a US election. They have no right to impose a party favourite on the country midterm.

I would say the change we need is as much cultural as political. We still live with the assumption that giving power to party members is “a good thing”. If you want to see the consequences, look around you: a Tory party in the control of a clique of narcissistic fantasists, and an institutionally racist Labour party which, like Caliban, cannot bear to see its reflection in the mirror. With ingratiating smiles, politicians thank the members who knock on doors and pound the streets. They talk as if activists were the bedrock on which democracy is based when they surely know it is the quicksand into which it is sinking.

• Nick Cohen is an Observer columnist