SUFFERING THE largest parliamentary defeat in modern history would give most prime ministers pause for thought. Not Theresa May. On January 21st she presented the House of Commons with her “Plan B” for Brexit. It turned out to be much the same as the Plan A which they had so decisively thrown out the week before. Mrs May still hopes that the European Union will agree to last-minute concessions, and that these will enable her to overturn the 230-vote majority against her deal. Yet with the clock ticking, that is a formidably tall order.

Through a combination of Britain’s weak negotiating position, the Conservative Party’s lack of a parliamentary majority and her own reluctance to compromise, Mrs May is running a zombie government that has lost control of the Brexit process. If no deal is struck by March 29th, Britain is due to fall out of the EU without any exit agreement.

It is thus increasingly urgent that Britain applies for an extension of the deadline, and that it uses the extra time to come up with a deal that wins the backing of MPs and voters. Mrs May’s unwillingness to contemplate such a course, or any other big change to her rejected plan, means that it is time for Parliament to step in.

The very idea incenses some of her supporters. They call it a constitutional “coup” by Parliament. They are wrong.

The process would be fiddly, certainly. Under amendments to be voted on by MPs on January 29th, Parliament itself would set the course for Brexit (see article). The goal would be to force the government to request an extension of the Article 50 negotiating period, stopping the clock and removing the risk of a no-deal exit, at least for now. This would be a sensible first step in any event. Whatever Britain does next—wrangle a new deal in Brussels, call a second referendum or even hold its third general election of the past four years—it is going to need more than the 30-odd working parliamentary days left before March 29th.

To push this through, MPs are proposing to suspend, for a time, parliamentary rules that give precedence to the government’s business. In effect, this would let them run the Brexit process, debating and passing motions that compel the government to take this or that course. Such a change would temporarily up-end a system that has been in place for roughly a century.

On the face if it, that might look like a coup. But it is not so simple. In normal circumstances a prime minister whose central project had been defeated by more than 200 votes would have been bundled out of office by now. Three things have kept the politically dead prime minister walking. First, under Conservative Party rules her backbenchers cannot attempt to turf her out until December, having tried and failed to do so last month. Second, despite lacking a majority in the Commons, she is unlikely just now to lose a confidence vote, because the risk of a radically left-wing Labour government terrifies both her Tory critics and the Northern Irish Democratic Unionists, who prop up her government. Last, the Brexit talks are so advanced that few people think there is time to go about finding a new prime minister.

If a majority of MPs vote to suspend the rules, they are acting within their rights—because who else but Parliament can set its procedures? Morally, the government can hardly accuse MPs of constitutional recklessness, when it has repeatedly tortured the rules in its attempts to sideline Parliament during the past two years of Brexit talks. Practically, the country is two months away from a chaotic no-deal outcome that no one had in mind when they voted to leave in 2016. For Parliament to intervene is a desperate measure, but these are just the times for it.

Ever since the 52%-to-48% referendum result, it has been clear that Brexit required trade-offs. Yet in a process that cried out for compromise and deliberation, Mrs May has resisted all attempts to involve Parliament. It is right that MPs should respond to her obstinacy by taking back control.