Foreign Secretary Boris Johnson resigned on Monday, following former Brexit minister David Davis out of the cabinet just days after Prime Minister Theresa May secured a hard-won agreement from senior ministers on an EU exit strategy.
"This afternoon, the prime minister accepted the resignation of Boris Johnson as Foreign Secretary. His replacement will be announced shortly. The prime minister thanks Boris for his work," an emailed statement from May's office said.
Johnson was the most high-profile member of May's cabinet and was one of the leaders of the Leave campaign. His departure will be seen as a bitter blow for the prime minister, who had hoped to bring her feuding cabinet together in support of her Brexit plan, which has yet to be agreed by the European Union.
Speculation that he or other disgruntled Leave campaigners unhappy with her handling of the negotiations might trigger a leadership challenge is already rising. However, no senior Tories are thought likely to be eager for another general election that could hand power to Jeremy Corbyn's Labour Party.
Former Tory chairman Grant Shapps told the BBC it was the wrong time for a leadership contest and he hoped it would not happen.
He said a contest would take three months and 'we physically do not have the time for that' before the UK is due to leave the EU.