Theresa May was only ever going to win approval for her Brexit deal by persuading MPs that it was the least worst option. Remain-supporting MPs, she hoped, would come to believe that her deal was the only way of preventing no deal. At the same time, she hoped that Tories worried about ‘no Brexit’ would see her agreement as the best way of ensuring that Britain actually left the EU. But with the Commons vote on May’s Brexit deal just days away, both parts of this strategy are in trouble. Little wonder that the Chief Whip sounded downbeat about the prospects of winning next Tuesday’s vote at cabinet this week.

A cabinet revolt has forced May to promise that if her deal is rejected, MPs can have a vote on whether to proceed with no deal or not. This means that those who dislike her withdrawal agreement because it involves leaving the EU or because it doesn’t point to a close enough relationship can vote against it but be confident that they can defeat no deal the next day.

Despite this, Brexiteers seem remarkably unconcerned about her deal being voted down next week, which compounds May’s problem. Many of them have convinced themselves that they’ll eventually get the Brexit they want, come what may.

Some believe that MPs will not manage to agree on anything — and May will end up supporting a no-deal Brexit when the vote comes on Wednesday. But this makes some heroic assumptions. If the government can’t successfully whip for its own deal, then why should it have more success doing so for no deal? It is also hard to imagine those cabinet ministers who went into open revolt to get a vote on the extension then backing no deal. When Julian Smith talked about losing the vote on no deal at cabinet on Tuesday, Philip Hammond picked him up on it — implying that he wouldn’t regard no deal being voted down as a defeat. Even if the government did whip for it, no deal would be highly unlikely to succeed.

Another scenario involves the Brexiteers in the Tories’ European Research Group bringing down the government by siding with Labour in a no-confidence vote. This would also involve the Democratic Unionist Party not backing the government. Under the Fixed-term Parliaments Act, voting no confidence in the government doesn’t necessarily lead to a general election. Instead, it starts a 14-day period in which a new government can try to gain the confidence of the House. So in theory, a no-confidence vote could lead to a new prime minister — without the need for a general election. But it is hard to imagine that a prime minister prepared to leave the EU with no deal could command the support of a House of Commons that is opposed to it.

Some Tory Brexiteers argue that, in such circumstances, a general election would be best. But who would lead them? The Tory party would also be the only British party opposed to a second referendum — so it would need to win a majority to be confident of stopping one. An election born of a Tory civil war (and general inability to govern) would hardly be the most propitious basis on which to ask for a fourth term in office; something that has been achieved only once in post-war history.

Amber Rudd and the other ministers who pushed for a vote on whether to request a Brexit delay believed they were being loyal to May: that the very prospect of extending the Article 50 process would push the ERG into voting for the deal. But so far, there aren’t signs of that happening. Many of them think that any extension would only be until July, when the new European Parliament starts work, and so doesn’t matter too much. Jacob Rees-Mogg has openly said that a few extra months won’t make much difference. Others — including the lawyer Martin Howe and the MEP Daniel Hannan — have gone further and argued that there are actually benefits to a 21-month extension.

But the real risk of the extension is what price the EU would ask Britain to pay. The EU is likely to agree to a delay: it has no desire to be blamed for a no-deal Brexit. But no one can predict with confidence how long the extension would be for, or what conditions it would come with. Any significant delay may also persuade MPs to attempt to have the House of Commons take charge of the process. They might force parliamentary votes on various Brexit options as an exercise to see what could command a majority. They would then seek to compel the government to implement the result.

All this would lead to a softer Brexit than May’s deal. It would, at the very least, result in a permanent customs union being negotiated. But some MPs would like to go further and push for a so-called Norway-plus arrangement, which would see the UK remain in both the customs union and the single market. This would leave the UK, in many respects, a non-voting member of the EU.

The other danger to Brexit is a second referendum. At the moment, there do not appear to be the numbers in parliament for this. But if the logjam continues, it might come to be seen as the only way to resolve the issue. But Brexiteers should remember that this parliament is highly unlikely to allow no deal onto the ballot paper.

British politics is so unpredictable right now that one should not rule out a sudden change in mood. If the DUP were content with the changes that Geoffrey Cox negotiates to the backstop, that might reduce the Tory rebellion enough for May to win the meaningful vote with the support of some Labour rebels. But, at the moment, it is hard to see May winning Tuesday’s vote.

May’s deal could have survived opposition from either those MPs who have never accepted the referendum result or those who wanted the cleanest of breaks with the EU. But the Prime Minister’s problem is that both groups are opposed to it. This makes it almost impossible for it to get a parliamentary majority. But given their differing motivations, both groups cannot be making the right call in opposing this deal. Time will tell which group is right and whether the Brexiteers are about to miss their best chance to secure this country’s departure from the EU.