Early last week a call came into the office of a senior cabinet minister from one of Boris Johnson’s team at Downing Street. No 10 was frantically lodging requests across departments for members of the government to go on the media the following morning to defend the prime minister – and face the inevitable barrage of near-impossible questions about “partygate”. Texts were exchanged. Agonised faces were pulled. Would it be a good idea? What was to be gained for the minister concerned? Was it just a hospital pass that required a decent excuse? In the end, a judgment was reached by the minister’s closest officials. “We have to do it, don’t we?” one said. “If we say no it will be a declaration of fucking war.” Ministers and their staff, as well as Tory MPs, have been making such difficult calculations for weeks now. Should they go out, publicly, in support of Johnson’s campaign to save his premiership? Or should they steer clear and shield themselves from association with their embattled leader’s efforts to justify what a large section of the public has concluded is completely unjustifiable breaking of Covid rules at the heart of power? For those currently in ministerial jobs, and with ambitions to stay or climb further up the ladder, the “partygate” crisis has meant many tough calls and fine judgments. With Rishi Sunak and Liz Truss limbering up for a potential leadership contest in the event of the PM being forced out, should other ministers look to the future, tip winks to one or the other, guaranteeing their support in the event of a contest? There has been talk in ministerial inner circles of “cutting deals”, of conveying back channel messages saying to Sunak or Truss that if you give me this or that job, I’ll be on board. And, the Observer has been told, there has been talk in other cabinet ministerial teams of whether their man or woman should think of a surprise leadership bid themselves. “That discussion has been had and will have been had elsewhere too,” said a senior source close to a minister. This weekend it is ordinary backbench Tory MPs who are feeling the most pressure – and for many of the more recent intakes, like never before. Johnson has been on the phone to many of them from Chequers, demanding and pleading for loyalty. In the coming week the senior civil servant Sue Gray is expected to publish her report into parties at Downing Street. So far, despite uproar among their constituents, fewer than a dozen Conservative MPs have gone public with calls for Johnson to go. But if 54 or more were to write to the 1922 committee chair Sir Graham Brady, a vote of confidence in the prime minister would have to be held. If he were to lose that vote, he would have to go. The Gray report is a moment of maximum danger for Johnson. Most Tory MPs are waiting to see what she says before making up their minds whether to strike against him. From hour to hour over the last week, the mood has oscillated from one of utter despair in Downing Street to one of revived hope. A low point came on Wednesday when the Tory MP for Bury South, Christian Wakeford, dramatically crossed the floor and defected from the Conservatives to Labour in disgust at Johnson’s leadership. The initial reaction in the media was that this could be the tipping point - the end for Johnson. But it was not so. Cabinet ministers immediately began attacking the defector, briefing viciously against Wakeford, even making claims about his private life. The effect of the defection was not what Wakeford had expected. Rather than being the catalyst for more to follow him, his switch to Labour, temporarily at least, brought the Conservative parliamentary party more together. “You will see many of those who have written letters calling for the PM to go, ripping their letters up now,” said a Tory grandee. “There is nothing that unifies us more than a traitor joining the enemy side. There will be more letters coming out of Graham Brady’s office now, than going in.” But no mood settles for long in this crisis. “It all comes in waves,” said one former Tory minister. “There will be one wave that crashes over the harbour wall and causes real damage to the PM. Then another which looks like being even bigger than the last, but then it fizzles out, out at sea.” No sooner had the Tory whips and No 10 taken heart from the Wakeford defection, however, than the waters were churned up again as senior Conservative MP William Wragg broke cover to suggest some of his colleagues had been effectively blackmailed and threatened with the loss of money for projects in their constituencies if they failed to support the government. Wragg has referred the matter to the police. Ahead of Gray’s report, everyone at the top of government is on tenterhooks. Its content could have seismic effects on many, many careers. She is said to have been “forensic” in her investigations into at least nine parties at Number 10 during periods of Covid restrictions, with six officials helping her comb through the details on logs of comings and goings from Downing Street. People who are in regular touch with Gray and know her mind say she will be both “fair” but also “ruthless”, because she is the kind of person who will see the breaking of Covid rules in lockdowns as no small matter, particularly for those who made the rules in the first place. But Downing Street is not giving up. Over the past few days it has thrown everything at announcements to show it is on the front foot, ones inevitably viewed by many as rushed attempts to push “partygate” down the news agenda. Announcements about freezing the BBC licence fee and use of the Navy to stop migrants arriving on UK shores have been followed by No 10 and Foreign Office warnings of the consequences of a Russian invasion of Ukraine. Some Tory MPs say it is working and that fewer constituents are complaining about parties than a week ago. “You only write to your MP once. The worst has passed,” said one. A senior Whitehall figure said he had never seen anything like the “save Johnson” campaign of recent days. “They will stop at nothing. This is full, full on. Even war in Ukraine.” But even if the prime minister survives the aftermath of the Gray inquiry, the road ahead is full of minefields that no amount of distraction will obscure. A cost of living crisis made worse by soaring inflation will be the backdrop for local elections in May. Several Tory MPs have told the Observer they have been told by their Conservative councillors not to go on the campaign trail, because MPs’ names are mud. Yesterday Ruth Davidson, the former Tory leader in Scotland, stuck the knife into Johnson. “I didn’t support him for the leadership and I believe what has been exposed to have happened during the last few weeks shows that he is unfit for office but, I mean, he is perfectly convivial company.” A former cabinet minister said that while Johnson was in deep trouble he found it near impossible to judge what would happen next, which way public and political sentiment would go. “I would say that he has a 50:50 chance of getting through the Sue Gray report,” said the senior party figure. “Then it depends what happens and how he leads. It is just impossible to say.”