UK chief negotiator Olly Robbins - the civil servant who masterminded Theresa May’s Brexit deal - will quit his role this summer.
Robbins, who has been a controversial figure among hardline Eurosceptics, will step down shortly after the new prime minister takes up his post at the end of July.
The race to become the new Tory leader is still being led by Boris Johnson, who is favoured as the new prime minister by about half of Conservative voters, whereas Jeremy Hunt has support from only about a quarter in the latest Opinium poll.
As the campaign to replace her continues, May will head to Brussels for a European Council summit where EU heads of state will continue discussions on who should be nominated for the EU’s top jobs.
May will step down following her final PMQs on Wednesday July 24 and Robbins is expected to follow shortly afterwards, although he has committed to a brief handover before he moves on, with reports he may take up a job in the City.
Robbins’s departure is the latest in a wave of top civil servants dealing with Brexit who have announced they will resign rather than take on the challenge of delivering Brexit within 100 days under the new leader.
Tom Shinner, director of policy and delivery coordination at the Department for Exiting the EU, and Karen Wheeler, director general of Her Majesty’s Revenue & Customs Brexit border delivery group, have both announced they will quit.
Hunt was asked about Robbins at a hustings in Manchester and said it was “a good moment to change our approach” to cheers from Tory members.
“I didn’t agree with the approach that we took in a number of areas of the Brexit negotiations,” he said.
“I was a loyal Cabinet minister - I think it’s very important the Prime Minister has a loyal foreign secretary - but I wasn’t a believer in the backstop and I didn’t believe it would get through Parliament, so I think this is a good moment to change our approach.
“I’m not going to say something about a civil servant who I know works incredibly hard, even though there are issues I disagree with him on.
“But I do think now is a moment that we have to get this right, deliver a different deal and one that can actually get through Parliament.”
Hunt is reported to have signed up former Canadian prime minister Stephen Harper to lead his negotiating team, alongside Crawford Falconer and Rona Ambrose, with the aim of securing a Canadian-style free trade deal, while Johnson is said to have recruited Sir Edward Lister.