Lee Cain has announced he will quit as Downing Street’s director of communications following a row over becoming the PM’s new chief of staff.
Cain, a former member of the Vote Leave campaign and former tabloid journalist, had been offered the powerful post in recent days.
He is a longtime aide of Johnson having served with him when he was foreign secretary and when he was a backbencher.
But his potential appointment parked concerns among some Conservative MPs that yet another member of the Vote Leave inner circle would lead the day-to-day running of the No.10 operation once Cummings steps back to focus on individual projects.
The prime minister’s partner Carrie Symonds also reportedly objected to plans to appoint Cain to the key role – an account that was not denied by No.10
Johnson’s appointment of Allegra Stratton to lead daily televised press briefings is also understood to have added to the friction inside No.10.
One ally of Cain said he has been mulling over leaving Downing Street for a quieter life having seen friends and allies do the same in recent months.
Tory MPs are likely to see this as an opportunity to urge Johnson to reset his premiership following a difficult few months during the pandemic.
Senior figures are understood to be urging Johnson and his team to appoint someone who knows and cares about the party and understands that the government depends on the support of backbenchers who have felt alienated in recent months.
According to one report, Cummings was said to be very unhappy about Cain’s departure and was considering following him out of the door.
The prime minister said Cain was a “true ally and friend” and will be “much missed”.
In a statement, Cain said: “After careful consideration I have this evening resigned as No10 director of communications and will leave the post at the end of the year.
“It has been a privilege to work as an adviser for Mr Johnson for the last three years – being part of a team that helped him win the Tory leadership contest, secure the largest Conservative majority for three decades – and it was an honour to be asked to serve as the prime minister’s chief of staff.
“I would like to thank all the team at No.10 – including the many unsung and incredibly talented civil servants – for their hard work and support during the last 18 months.
“And most of all I would like to thank the prime minister for his loyalty and leadership.
“I have no doubt that under his premiership the country will deliver on the promises made in the 2019 election campaign and build back better from the coronavirus pandemic.”
Johnson said: “I want to thank Lee for his extraordinary service to the government over the last four years.
“He has been a true ally and friend and I am very glad that he will remain director of communications until the new year and to help restructure the operation. He will be much missed.”