One of the few predictable features of the seemingly endless Tory party civil war over Europe is that the truces never hold for long. And when they are broken and the infighting resumes, the battles are even more bloody than they were before.

So it has proved in 10 extraordinary days since Theresa May tried to unite her cabinet over Brexit at Chequers. “She bet the entire farm on the Chequers deal holding,” said a former cabinet minister on Saturday. “But now we are in a far worse mess than we were before.”

No one in May’s team could have predicted in their wildest nightmares how the past week would unravel. First came the resignations of her Brexit secretary, David Davis, and foreign secretary Boris Johnson – just three days after they had professed themselves loyal to the Chequers accord. Further resignations of more junior figures in the government followed. Downing Street staff prayed that was the end of it.

Enter Donald Trump. The US president gave the Brexit crisis a transatlantic rocket boost that propelled it to new heights. In an interview with the Sun, Trump laid into the Chequers deal, saying it would kill off hopes of a US-UK trade deal, then criticised his host for not listening to his advice on Brexit, and even said Johnson – his eyes on May’s job – would make an excellent prime minister.

This weekend deep unhappiness at May’s attempts at Chequers to foist a soft Brexit on the country is evident at all levels of her party. “The local associations are in complete turmoil,” said one senior Tory MP. The fact many Conservatives, particularly those who backed Leave in the EU referendum, are in despair is borne out by an Opinium poll published in the Observer today showing Tory support haemorrhaging and a surge in backing for Ukip, which had seemed dead on its feet earlier this year.

The numbers who approve of May’s leadership in general, and on Brexit, have nosedived. The Tories, who were two points ahead of Labour five weeks ago, are now four points behind Jeremy Corbyn’s party. Brexit is fast rising up the list of subjects the public see as most pressing.

A senior Tory backbencher on the 1922 committee executive said on Thursday that May had the “best chief whip ever” and that he would still save her. “He is called Jeremy Corbyn. Just mention the threat of a Corbyn government and our people come into line.” But while playing the Corbyn card works with many MPs, if their local party associations rise up against May en masse they will have to move, and she is doomed.

Last night senior party sources made clear that Sir Graham Brady, chairman of the 1922 committee, had not (yet) received the 48 letters from Tory MPs (15% of the parliamentary party) that would require him to trigger a leadership contest. Party managers and the Tory whips are now setting their sights on just getting through the next few days before parliament retires for the long summer break on 24 July. “Most people just want to get out of Westminster. And that will be her sole objective now,” said another senior Tory.

But even surviving the coming week without further crises will be easier said than done. The next five days could be just as difficult as the last 10. Brexit-related legislation on trade and customs returns to the Commons tomorrow and Tuesday.

It is likely that Tory Remainers will back away from trying to inflict defeat on May over the customs union – “the poor woman is in such a desperate situation that I think we have to wait until September”, was how one hardline Remainer put it.

The bigger problem for May could, however, now come from the other flank: the hard Tory Brexiters on right of the party who see the Chequers plans as an appalling betrayal. There are strong rumours that some in the European Reform Group led by Jacob Rees-Mogg, who has put down a series of wrecking amendments, could refuse to back either bill by abstaining or voting against a third reading.

If all the opposition parties vote against, as most expect them to, it would take only seven Tories to abstain or four to vote against to inflict what would be a devastating blow on the prime minister. To lose key pieces of Brexit-related legislation would suggest the government was unable to govern.

Allies of Davis say he will probably make a resignation speech in the Commons on Monday, the same day Johnson is expected to resume his Daily Telegraph column with another blast at May’s soft-Brexit blueprint.

Also on Monday talks on Brexit will resume between British and EU officials. The new Brexit secretary, Dominic Raab, will meet Michel Barnier in Brussels later in the week for the first time. If the signs from those meetings are that UK government proposals are unacceptable to the EU, it will be back to square one. Then on Wednesday May will face the full 1922 committee of Tory backbenchers at their “end of term” meeting. Normally it is an occasion for banging fists on tables in a show of loyalty. “If we manage that this time,” said one former minister, “it will be entirely for show.”

What is now clear is that, even if Brussels agreed a deal based even loosely on the Chequers agreement, it would be unlikely to pass through the Commons when a “meaningful vote” is held in late autumn.

Labour says it fails all its six tests and has made clear it will vote against. Tory hard Brexiters would rather have no deal at all than an arrangement that they say would leave us half in and half out. Many Remainers take the same view, though for very different reasons: that it would leave the UK worse off and weaker, neither free to strike out alone nor fully in the single market and customs union which is the minimum they want.

They say we would be trapped without the full benefits of the EU economic system but subject to many of its rules, which we would be unable to influence. The Chequers deal was supposed to unite the cabinet and Tory party. Instead it has united almost all wings of the Brexit debate behind the view that it would deliver the worst of all possible worlds.