LONDON — Liz Truss won the ruling Conservative Party’s leadership contest in the United Kingdom on Monday.   Foreign Secretary Truss will replace Boris Johnson as the country’s new prime minister.

In the runoff, Truss, 47, beat former Chancellor of the Exchequer Rishi Sunak by winning approximately 57.4 percent of the Conservative Party members’ vote, Graham Brady, chair of the party’s backbench 1922 Committee, announced Monday.

The voting took place a month after Johnson was forced to step down following an avalanche of ministerial resignations over his scandal-plagued leadership.

The formal handover is scheduled for Tuesday after Truss and Johnson meet Queen Elizabeth II, who is staying at her Balmoral estate in Scotland.

Truss will be Britain’s third female prime minister after Margaret Thatcher and Theresa May. She faces the immediate tasks of tackling the worsening cost-of-living crisis and handling a Brexit arrangement about Northern Ireland to avoid antagonizing the EU.

“I will deliver a bold plan to cut taxes and grow our economy. I will deliver on the energy crisis, dealing with people’s energy bills, but also dealing with the long-term issues we have on energy supply,” she said in her victory speech after the result was announced.