Dominic Cummings quit as Boris Johnson’s most powerful aide and will leave the U.K. government by the end of the year, throwing the future direction of the prime minister’s entire political project into doubt.
The resignation, confirmed by a person familiar with the matter, brings to an end 17 months of combative and often controversial influence of a small group of pro-Brexit officials over the British government.
Cummings is the second key adviser to Johnson to go in the space of a day, after tensions blew up over the way the prime minister’s inner circle operates. Late on Wednesday, Communications Director Lee Cain — who worked with Cummings and Johnson to deliver the 2016 Brexit referendum vote — announced he was standing down.