Theresa May has turned democracy against itself. She has been seduced by the siren evidence of the 20-point lead in the polls, and she will have a general election, the one she said again and again that she would not call. And it will almost certainly return her with a thumping majority that will allow her to run the Brexit negotiations just as she wants.

There will be no obligation on her to reflect the views of the minority position. She will leave the remainers of England disempowered. She has made a Scottish referendum inevitable, and a border poll in Northern Ireland infinitely more likely. She is resetting politics in a way that will entrench division. We will all rue this day.

May has trashed her brand. She did that once before, with that “nasty party” speech aeons ago, in 2002. That damaged her. This will do something infinitely worse. It will damage politics, not only in the short term, but for a generation.

On the way, she is not only making a nonsense of her signature determination to treat political process with due respect, not to treat politics as a game – she has rebranded all opposition as game-playing.

She is betraying, too, the idea that she wants a different kind of Britain. If she was trying to escape the binds of her loony Brexiteer fringe, she would craft positions that can garner cross-party support. If she really wanted to make life better for the just-about-managing, she would not back down on any useful measure as soon as her backbenchers bare their teeth.

She knows exactly what she is doing. She revealed as much at the Downing Street lectern when she abandoned her faintly plausible riff about needing a majority in parliament in order to make orderly progress, and said instead the election was “all about leadership”. She denounced Jeremy Corbyn, she dismissed the Lib Dems as mere props for a failing opposition, and she called down Nicola Sturgeon as if she were a spectre to haunt southerners’ nightmares.

Labour has got it wrong again. Corbyn says there will be no obstacle to an early election. Just when parliament ought to fight back in its own defence and resist the call for a general election, the leader of the opposition does just the opposite. He should hurl May’s own words back in her face. All those calls for stability, and for healing, and for no cheap tricks with election timing: they should be weaponised. This is no way to heal. It is a deliberate attempt to bulldoze MPs over the cliff. She thinks they won’t dare to say they are not prepared to go to the country.

But of course, that is not the point: the point is that MPs and peers, without disrespecting the intent of the no vote, are determined to make the outcome of Brexit a thought-through, coherent outcome that will protect the economy, the rights of EU citizens here and British citizens abroad, and preserve important social and environmental protections. Without them as a sea anchor, without the cover of a reluctant parliament, May really will go naked into the negotiating chamber.

Play Video 6:52 Prime minister Theresa May calls general election for 8 June – full video statement

So there is all to play for. She cannot have a general election without a two-thirds majority in the Commons. Opposition MPs (and self-respecting Tories) must insist that this is not the time and not the way to overturn the Fixed Term Parliament Act – an act that was drafted expressly to stop this kind of brutal exploitation of the UK’S flaky first past-the-post electoral arrangements.

Remember 1931, the last Tory attempt to expel Labour from power for a generation. Labour won 28% of the vote, but just 52 seats. Don’t let it happen again.