LONDON (AP) — British Prime Minister Boris Johnson’s top adviser plans to step down at the end of the year after a bruising battle for influence at the heart of the British government fueled by tensions over Brexit and the COVID-19 pandemic.

Amid speculation that he would leave the government, Dominic Cummings told the BBC late Thursday that he planned to be “largely redundant” by Christmas. Political commentators had suggested Cummings would step down after one of his allies was denied an appointment as Johnson’s chief of staff.

Cummings, a chief architect of the campaign to have Britain leave the European Union, has been a divisive figure inside the Conservative government since Johnson became prime minister 16 months ago. His position weakened earlier this year after he drove hundreds of miles across England after contracting COVID-19, violating national lockdown rules and leaving the impression that elite officials did not have to obey the same infection-control restrictions as everyone else.

The episode fueled criticism of the government’s handling of the pandemic after delays in the expansion of testing and efforts to avoid a second national lockdown in England. That lockdown was finally imposed last week, but it couldn’t stop the U.K. from becoming the first country in Europe with more than 50,000 virus-related deaths.

Nicknamed “Boris' brain,'' Cummings has also been the target of complaints from senior members of Johnson’s Conservative Party, who say that unelected advisers in the prime minister’s Downing Street office were effectively running the government, sidelining ministers and Parliament.

Bernard Jenkin, chairman of an influential committee of Conservative lawmakers, said Cummings’ resignation is an opportunity for Johnson to “reset how the government operates.”

“I would suggest there are three words that need to become the watchwords in Downing Street — they are respect, integrity and trust,” Jenkin told the BBC. “And certainly in the relationship between the Downing Street machine and the parliamentary party, there’s been a very strong sense that that has been lacking in recent months.”

Despite winning an 80-seat majority in the U.K.'s general election last December, Johnson’s government was forced into a series of embarrassing policy reversals in recent months, stoking criticism that Cummings was giving the prime minister bad advice.

In addition to changing his stance on lockdowns, Johnson backtracked on decisions to let Chinese technology giant Huawei participate in building Britain’s new mobile phone network and abandoned the use of an algorithm to assign grades to students after annual tests were canceled due to the pandemic. He also retreated from not extending free meals to poor children when schools were closed as Britain faced rising unemployment due to the pandemic.

In a January blog post, Cummings called for changes in the way government works, claiming that the civil service didn’t have enough expertise in some fields. He infamously said “weirdos and misfits with odd skills” could help the government develop better policies.

In that post, Cummings said he wanted to make himself “largely redundant” within the next year.

In his Thursday interview with the BBC, Cummings said rumors that he had threatened to resign this week were untrue, but that “his position hasn’t changed since my January blog.”

Transport Secretary Grant Shapps downplayed Cummings’ departure, saying he has achieved many of the things he set out to do.

Cummings’ signature policy goal was Brexit — ensuring Britain’s departure from the EU — and that process is scheduled to be completed at the end of this year. More recently, he has taken the lead in rolling out mass testing to help control Britain's COVID-19 outbreak, and that program is now being rolled out.

“It’s always been good to have somebody in the room who sort of shakes things up, asks why, doesn’t take no for an answer,” Shapps said. “And that’s been very much the way Dominic Cummings has been able to bring his talents to No. 10, but he’s ready to move on.”

But Cummings has been criticized for creating an adversarial relationship between the prime minister’s office and those he thought stood in his way, including civil servants, the BBC and backbench lawmakers.

Johnson, with Cummings’ support, has structured his premiership as an insurgency with one overriding goal: to take Britain out of the EU, deal or no deal.

But from the start, some argued that Cummings’ adversarial style was unsuited to the day-to-day operations of government. He defied convention by showing up for work in baggy sweaters and blue jeans, and alienated much of the political establishment by ignoring the advice of civil servants and senior Conservative Party lawmakers.

Those constant confrontations proved to be his undoing. The end came after reports that Cummings’ Vote Leave ally Lee Cain would be named Downing Street chief of staff. The appointment would have cemented the Cummings faction’s role as chief advisers to the U.K.'s highest officeholder.

But the move backfired, reportedly because Johnson’s fiancée, Carrie Symonds, a former Conservative Party director of communications, intervened, raising concerns about the appointment from the party’s rank and file. Johnson decided not to promote Cain, putting Cummings in jeopardy.

Jenkin said there has also been a breakdown in Johnson's government, with Johnson appointing inexperienced Cabinet ministers then dictating policies to them, rather than having ministers take responsibility for their departments.

Cummings’ departure is an opportunity to reshuffle the government and bring in more experienced ministers, Jenkin said.

“If you don’t have the corporate memory, well then history repeats itself and people make the same mistakes, or certainly mistakes that can be avoided,” Jenkin said.

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