Lee Cain, a former Vote Leave official and tabloid journalist, said in a statement it was “an honour” to be have been offered the position, but confirmed his imminent departure in a sign of a bitter power struggle at the heart of government.
It is unclear whether the offer of the role of the prime minister’s chief of staff, which is currently vacant, was withdrawn before Mr Cain stepped down amid claims that some opposed his promotion – including Mr Johnson’s fiancee, Carrie Symonds.
Earlier, Downing Street refused to answer journalists’s questions over the position of Mr Cain, who has served at Mr Johnson’s side since he was foreign secretary under Theresa May’s premiership and is also close to senior adviser Dominic Cummings.
His appointment as chief of staff would have entrenched the hard Brexit position at the top of No 10 at a time when some are trying to persuade the prime minister to reset his administration for the years after the UK transition out of the European Union.
But in a statement, Mr Johnson said on Wednesday evening: “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.”
Mr Cain, who in his past career as a journalist once chased around high-profile politicians during election campaigns donning a chicken costume for the Daily Mirror, said: “After careful consideration I have this evening resigned as No 10 director of communications and will leave the post at the end of the year.”
He added it had been a “privilege” to work for Mr Johnson over the last three years, helping him to succeed Ms May as Conservative leader, and working on the December general election campaign that delivered the largest Tory majority for three decades.
“It was an honour to be asked to serve as the prime minister’s chief of staff,” he said. “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.”
Immediately after his resignation statement was published, the BBC reported Mr Cummings, a fellow official on the Vote Leave campaign during the 2016 referendum who had counted Mr Cain as an ally, was considering his position.
The government’s chief Brexit negotiator David Frost was also reported to have been on the brink of resignation, but this was later walked back by Downing Street insiders.
Speaking earlier, Sir Geoffrey Clinton-Brown, a senior member of the 1922 Committee of backbench Conservatives, said MPs needed somebody to “get hold of” in No 10, after months of growing discontent between the prime minister’s office and the parliamentary party over the coronavirus strategy and a series of U-turns on issues such as free school meals for disadvantaged children during the school holidays.
“I think it’s a good thing that somebody would keep an overall view on it,” the senior backbencher said. “I think it’s important to have a chief of staff.”
Responding to Mr Cain’s departure, a Labour spokesperson said: “On the day the UK became the first country in Europe to report 50,000 coronavirus deaths and the public endured another day of lockdown, Boris Johnson’s government is fighting like rats in a sack over who gets what job.
“It is precisely this lack of focus and rank incompetence that has held Britain back. The public deserve better than this incompetence and divided Conservative government.”
