The next prime minister for the U.K. to be announced Monday

Britain's Prime Minister-elect Liz Truss pledged to deliver on a range of issues after being named the new Conservative Party leader on Monday. Truss will be the U.K.'s third female prime minister, following Margaret Thatcher and Theresa May.

Adrian Dennis / Adrian Dennis

Britain’s Conservative Party will formally announce its new leader at a conference center close to the country’s parliament on Monday, with the current foreign minister, Liz Truss, widely expected to secure the title – and the role of prime minister.

Truss has spent the summer campaigning against her opponent for the Conservative party leadership, the UK’s former finance minister, Rishi Sunak. The contest has been decided by the votes of less than 200,000 grassroots party members, rather than a national electorate.

The new prime minister will be formally appointed by Queen Elizabeth on Tuesday, after Boris Johnson has met with the monarch in Scotland to tender his resignation. Johnson, who has acted as a caretaker for the past few months, was laid low by a succession of scandals that crescendoed in the first half of this year. He lost the support of many fellow conservative legislators, and indeed many ministers in his own government, which forced him to resign.