Boris Johnson has one final chance to overhaul a dysfunctional Downing Street operation beset by crises, Conservative MPs have warned after bitter infighting triggered the sudden departure of one of his closest aides. A string of Tories said the resignation of No 10 communications director Lee Cain, after Johnson’s fiancee and inner circle blocked his promotion to chief of staff, epitomised a No 10 riven by factions, cut off from backbench MPs and lurching from crisis to crisis. It came amid renewed rumours that Dominic Cummings, Johnson’s chief adviser and another alumnus of the Vote Leave campaign, could also be planning to quit by Christmas or even earlier. Responding to speculation over his departure, he told the BBC that his “position hasn’t changed since my January blog” when he said that he wanted to make himself “largely redundant” by the end of 2020. One senior Tory MP openly called on Johnson to “get a grip” on the situation. Others expressed despair at a spectacle which saw Carrie Symonds, Johnson’s fiancee and a former Tory party press adviser, join those protesting at the promotion of Cain at a time when the government is battling Europe’s highest coronavirus death toll and a looming Brexit deadline. One MP, who asked not to be named, said: “They’re children. Ideologues and self-obsessed fools.” Another, also speaking anonymously, said the prime minister must shoulder the blame for internal rows at such a pivotal time for the country. The government under Johnson has performed a series of major pandemic U-turns, involving national lockdown measures, furlough support, exam results and free school meals. “The view from a lot of colleagues today is that we are witnessing the end of hope in Boris as a second-term PM,” they said. “He has left a vacuum at the centre of government and that is being filled by Cummings, who does not like the Conservative party, and his fiancee, who lives above the shop. It’s like the script from a bad soap opera.” Official figures showed a record 33,470 UK daily coronavirus cases on Thursday. At a Downing Street press conference, the medical director of NHS England, Stephen Powis, said the number of Covid-19 inpatients had more than tripled in a month to more than 12,700. Appearing alongside him in Downing Street, the business secretary, Alok Sharma, insisted the internal battles had not distracted ministers. “I can tell you that all of us in government are focused on one thing, which is protecting lives and protecting livelihoods,” he said. But a senior backbencher, Sir Roger Gale, said Downing Street should be “concentrating all of its efforts on the pandemic and on the end game of Brexit”, and called for Cummings to be ousted in favour of a proper chief of staff. “Frankly, this is a distraction that cannot and should not be allowed to take place, and the prime minister has got to get a grip on it,” he said. “For my money Cummings is a liability and what the prime minister needs and deserves is a first-rate chief of staff who is a serious heavyweight. I think the expression currently in use is big boy pants.” Tobias Ellwood, the chair of the defence select committee, told the Guardian that Downing Street was “overdue a wider shakeup” and struggling to get on top of the wider policy agenda. Johnson was “facing an unprecedented series of challenges, the scale of which we’ve not seen since the war”, including Covid, Brexit and an economic downturn, Ellwood said. “With the new US president focusing on re-establishing western resolve and tackling climate change we should be also seeking to play a more active role on the global stage,” Ellwood said. “The machine of government must adapt otherwise it will be overwhelmed.” Downing Street declined to comment on reports that Cummings had threatened to resign in fury over the way Cain, his close ally, is perceived to have been forced out, or that Johnson is still aiming to appoint a new chief of staff to get a grip of the No 10 operation. It confirmed that James Slack, currently Johnson’s lead spokesman, would take on Cain’s job. Unlike Cain, he will remain as a civil servant rather than a political appointee. One strongly pro-Brexit MP said he hoped the changes would mark a “reset” but warned time was running out for Johnson to steady the Downing Street ship. “I’m not driven by any animosity towards Dominic Cummings. I just think it’s an operation which is failing,” the MP said. “You don’t put the guru in charge of management. If you throw out all these ideas, it’s for others to see if they are actually workable. We need a chief of staff who makes it their business to talk to people. “This is really important. If this reset doesn’t work, and we have a bad set of elections in May, it’s just going to get worse.” Another was more blunt: “There’s a cabinet revolt against Dom’s reign of terror. Reducing the power of the Vote Leave gang is desirable and hopefully a turning point.” A source close to a cabinet minister said: “The problem with Downing Street is they have remained in campaign mode since winning the election. They are warring with everyone in Whitehall and that’s down to Cummings. “They just don’t seem to know how to govern. Eleven months in, they should be leading a united front but they are still working in the image of Vote Leave.” A series of backbenchers said they had virtually no contact with Cain or Cummings but despaired about both government messaging and the lack of liaison with MPs. “It ends up with all these flawed bills, requiring endless U-turns, and MPs don’t feel listened to or appreciated,” one said. “We didn’t come into this job to be a glorified chorus.” News of Cain’s departure, which will happen at the end of the year, emerged in a statement from Downing Street sent out late on Wednesday. It comes after Johnson is understood to have offered him the chief of staff role last week, prompting significant pushback inside No 10, with Symonds heavily involved, as well as Munira Mirza, head of the No 10 policy unit. The infighting has in part been sparked by the arrival at Downing Street of Allegra Stratton, a former journalist and adviser to Rishi Sunak, the chancellor. Stratton is to be the face of planned daily televised Downing Street media briefings. Cain had devised the idea, but is known to have opposed Stratton getting the job. He had also clashed with Symonds previously. Keir Starmer described the scenes as “pathetic”. The Labour leader told LBC radio: “I think millions of people will be waking up this morning scratching their heads, saying, ‘What on earth is going on?’ We’re in the middle of a pandemic, we’re all worried about our health and our families, we’re all worried about our jobs, and this lot are squabbling behind the door of No 10.”