Daniel Korski has dropped out of the race to be the Conservative mayoral candidate for London hours after Downing Street and senior Conservatives deemed groping allegations made against him as “very serious”. Daisy Goodwin, a novelist and TV producer, alleged in a piece for the Times that he had put his hand on her breast during a meeting at Downing Street when he was an adviser to David Cameron, 10 years ago. She submitted a formal complaint to the Cabinet Office about Korski’s alleged behaviour on Tuesday evening. In a statement, the tech entrepreneur said that while he still “categorically” denied the claim, he had decided, “with a heavy heart”, to step down from the race as “the news agenda is becoming a distraction from the race and the Conservative party”. Earlier, Rishi Sunak’s spokesperson said the prime minister would encourage anyone with complaints against former staff members to come forward, but dodged questions on whether the prime minister thought Korski should suspend his campaign. “Obviously these allegations are very serious,” Sunak’s spokesperson said. “They are allegations that have obviously been denied by Daniel Korski himself. They should be handled in the proper way.” In a statement, Korski said: “The pressure on my family because of this false and unproven allegation and the inability to get a hearing for my message of ‘the London Dream’ makes it impossible for my campaign to carry on. “I am proud of having run a positive campaign that championed new ideas, technology and talent.” Goodwin said she felt “entirely justified” in naming Korski, a decade after the alleged incident took place, as she said more women had come forward with “very interesting stories”. Pressed during an interview with the BBC if she was “absolutely certain” the alleged event had taken place, Goodwin said: “Yes, it happened to me 10 years ago. But when something like this happens to you, you know that it happened to you because you were there, you felt it, you felt amazed, shocked and rather humiliated. “To ask me if I’m certain is to ask me if I’m making it up. That’s not the case. I can’t say I’m a victim, but I was shocked by it. “Since I wrote my piece I have been contacted by other women with some very interesting stories, which clearly I can’t talk about. But I feel entirely justified in having written the piece and naming him.” When he was deemed the Conservative frontrunner of the London mayoral race, Korski had the support and endorsement of senior Tories including the levelling up secretary, Michael Gove, and the education minister Robert Halfon. Halfon is said to have “paused” his support on Tuesday, with the children’s minister Claire Coutinho following suit. Coutinho called on the Cabinet Office “swiftly” to follow up Goodwin’s formal complaint about Korski’s alleged behaviour, and said his alleged actions had “no place in society”. “It’s really difficult to have that kind of experience at work,” Coutinho said when asked about the allegations. “It’s really important that we establish the facts.” Goodwin’s groping allegation has raised questions over party processes on handling complaints. The Conservative party is not investigating the allegation as the party “does not conduct investigations where the party would not be considered to have primary jurisdiction over another authority”, a spokesperson said. The prime minister’s official spokesperson suggested a “serious allegation” would be looked at by the “appropriate authority” regardless of the passage of time. Since the Cabinet Office has refused to confirm receipt of the formal complaint, Goodwin posted a screengrab to Instagram of an email receipt from the Cabinet Office with the subject line: “Formal complaint about Daniel Korski urgent.” The post included the caption: “Who is running the country?” It is unclear if an investigation will go ahead now Korski has quit the race. The remaining candidates are Susan Hall and Mozammel Hossain, with the winner to be announced on 19 July. Hall, a London assembly member, said Korski should still be investigated. “Daniel fought a hard campaign with lots of fresh ideas and I appreciate his contribution to the debate. The allegations against him are serious and it is right that they are investigated in the proper way,” she tweeted. Hossain, is a defence barrister with no political experience. Tory insiders say he is Downing Street’s pick. He has been nicknamed “Mysterious Moz” due to his virtually nonexistent public profile.