T HERESA MAY is fond of making promises. On no fewer than 108 occasions, the prime minister has pledged that Britain will leave the European Union on March 29th, the deadline for Brexit under the Article 50 process that she triggered two years ago. Yet with just over a week to go, she wrote on March 20th to the president of the European Council, Donald Tusk, to ask for more time. Even as she told Parliament that, against her previous promises, she was seeking an extension of the deadline to June 30th, she offered yet another vow. “As prime minister, I am not prepared to delay Brexit beyond June 30th,” she said, implying that if this happened she would resign.

The question is whether anyone now believes promises made by a prime minister whose authority is shot. The Brexit deal that she struck with EU leaders four months ago has twice been voted down by the House of Commons, by enormous margins. Any control she once had over MP s, even from her own Tory party, has long gone. Even her own cabinet ministers now seem ready to defy her, whether when voting in the Commons or in leaks to the press.

EU leaders, who gathered in Brussels for a summit the day after Mrs May sent her letter, are keenly aware of all this. Any extension to the Article 50 deadline requires their unanimous agreement. Most observers believe this will eventually be forthcoming. Yet several leaders were soon threatening to say no. As Michel Barnier, the EU ’ s Brexit negotiator, put it, they wanted to know what an extension was for, how it would advance ratification of the deal and whether there was a risk of being in the same position in three months’ time. Mr Tusk responded to Mrs May by saying that a short extension was possible—but only if MP s approved the Brexit deal.

Despite this tough line, EU leaders do not want to precipitate a no-deal Brexit, for which neither they nor Mrs May are prepared. But they could quibble over how long the extension should be. Last week Mrs May herself warned that, if MP s voted down her deal again (which they did), any extension might have to be long. David Lidington, her deputy, even called a short, one-off extension “downright reckless”, because it made a no-deal Brexit far more likely. EU leaders were deliberating as we went to press. One possibility was that they might agree in principle to an extension, but hold back from legally endorsing it until late next week, right up against the March 29th deadline.

A big complication is the European elections in late May. Mrs May insisted that it would be quite wrong for Britain to participate in these elections. Some in Brussels think this suggests a May 26th deadline, but British officials reckon an extension to June 30th is possible because the new European Parliament does not meet until July 2nd. Yet an earlier deadline may be April 12th. If MP s have not backed the Brexit deal by then, the government will be under pressure to legislate to allow it to hold European elections should they become necessary.

On Westminster bridge

After the summit, the focus will return to Westminster. Having lost the first two Commons votes on her deal by the crushing margins of 230 and 149, Mrs May plans to hold a third next week, partly to justify to fellow EU leaders a short Article 50 extension. The government has also promised to allow indicative votes on what other kind of Brexit might secure a majority. Mrs May has previously accused MP s of saying only what they do not want, not what they do—yet she herself has stopped indicative votes before. If she does so again, MP s will have another go at taking over the agenda (they failed by only two votes earlier this month).

A new problem emerged this week in the form of the Speaker of the Commons, John Bercow. Without warning the government, he ruled on March 18th that it could not put the Brexit deal to a third vote in the current parliamentary session unless it was changed in substance. His ruling is based on precedents set out in Erskine May, the bible of parliamentary procedure, that date as far back as 1604. Both pro- and anti-Brexit MP s hailed it as a victory for the legislature over the executive. In contrast the cabinet was united, said one minister, only in its fury at the Speaker, who is suspected of wanting to sabotage Brexit.

Despite Mr Bercow, the prime minister will keep trying to bully MP s into backing her deal. Her strategy is to peel off groups opposed to it, starting with the Northern Irish Democratic Unionist Party (DUP). She will again tell them the only alternative is a no-deal Brexit, even though Parliament has voted against such an outcome. If the DUP falls in line, many hardline Tories may follow. Although Labour’s leader, Jeremy Corbyn, shows no sign of co-operating, some of his MP s could switch—but, in a catch-22, only if the vote is likely to be won, as they don’t want to wreck their prospects in the party for nothing. Mr Bercow’s ruling may prevent a string of repeated votes. But if Mrs May can assemble a majority in a few days, ways can be found round the Speaker.

That remains a big if. Since Mrs May runs a minority government, winning a majority is hard, especially given her habit of castigating MP s. It is harder when MP s and even ministers freely defy their party whips, as has repeatedly happened in recent weeks. And it is harder still when parties are split, with internal caucuses like the hardline pro-Brexit European Research Group running their own whipping operation. Nikki da Costa of the Cicero Group consultancy, previously Mrs May’s director of legislative affairs, says controlling Parliament is now all but impossible thanks to a cocktail of “no party discipline, extensive cross-party collaboration and the unpredictability of the Speaker”.

This matters because one vote for the Brexit deal is not enough. Parliament would then have to pass a withdrawal agreement bill. Precedents are not encouraging. In 1971 Edward Heath’s Conservative government won the vote to approve entry into the European Economic Community by 112 votes, but its majority at second reading of the subsequent act shrank to just eight. According to the Institute for Government, a think-tank, approval of the bills to ratify the EU ’ s Maastricht treaty took 41 sitting days and dozens of separate parliamentary votes.

And that would be just the end of the beginning. Negotiations on future relations with the EU , ranging from trade to security co-operation, would then start, based on the political declaration that accompanies the withdrawal agreement. This has no legal force and is nebulously drafted. Worse, the timetable would be hideously short: a transition period that can be extended only until December 2022. Free-trade agreements covering such a wide range typically take several years to conclude—and several more to ratify. Any deal with Britain must be approved by all national and several regional parliaments in the EU .