British Prime Minister Boris Johnson resigned on Thursday.
Mr Johnson had been hanging onto power despite the resignation of a string of his top ministers.
On Thursday, the man he appointed as finance minister less than 48 hours earlier publicly urged Johnson to quit.
Defence Secretary Ben Wallace also called on Mr Johnson to quit but said he would stay in his role to protect national security.
Johnson plans to carry on as prime minister until a new leader is chosen later in the summer, a task that can take up to two months.