Sir Alan Duncan has quit as a Foreign Office minister ahead of Boris Johnson becoming Prime Minister.
Sir Alan, who is a vocal critic of the leadership favourite, made it clear he could not countenance serving under him.
His resignation letter, submitted to Theresa May, was littered with veiled digs at Mr Johnson and his performance as foreign secretary.
Mr Johnson is almost certain to win the Conservative leadership election tomorrow and become Britain’s next PM
Up to 12 ministers are expected to follow suit and quit rather than waiting to be fired as the new Prime Minister forms his government.
I resigned as Foreign Office minister this morning. Here is my letter to the Prime Minister. pic.twitter.com/1kpt7rHsF0— Sir Alan Duncan MP (@AlanDuncanMP) July 22, 2019
The first ministerial departure is a signal of the difficulties the next PM will face taking office, with wafer-thin majority and a bitterly divided Tory party showing little sign of healing its rifts over Brexit.
Chancellor Philip Hammond said yesterday he would quit if Mr Johnson wins the ballot.
He told the BBC’s Andrew Marr: “I’m sure I’m not going to be sacked because I’m going to resign before we get to that point.”
Mr Hammond is a fierce opponent of a no-deal Brexit, and has warned Mr Johnson his promise to negotiate a new Brexit deal before 31 October is impossible.
He said yesterday: “Assuming that Boris Johnson becomes the next prime minister, I understand that his conditions for serving in his government would include accepting a no-deal exit on the 31st of October, and it’s not something that I could ever sign up to.”
Justice secretary David Gauke told the Sunday Times he would hand in his notice if Mr Johnson becomes PM, saying a no-deal Brexit would be a ‘humiliation’ for the UK.
Sir Alan Duncan has been publicly critical of Mr Johnson over his handling of the resignation of the former UK ambassador to Washington Sir Kim Darroch, who was forced out of his job after letters he wrote criticising Donald Trump were made public.
Sir Alan accused Mr Johnson of ‘contemptible negligence’ and accused him of ‘throwing [Sir Kim] under the bus’ after failing to support him over the leaked memos.
In June he described Mr Johnson as a “circus act” and last year he promised to end the former foreign secretary’s political career over his comparison of Theresa May’s Brexit deal to a “suicide vest”.
Other ministers rumoured to be thinking about quitting include de facto deputy PM David Lidington and international development secretary Rory Stewart.