British Interior Minister Theresa May will take over as UK’s prime minister on Wednesday.
It comes after her rival Andrea Leadsom abruptly terminated her short-lived leadership campaign.
May, 59, will succeed David Cameron, who announced he was stepping down after Britons voted to quit the EU.
May and Leadsom were to contest a ballot of Conservative party members, with the result to be declared by September 9. But Leadsom unexpectedly quit on Monday after a campaign dogged by ill-judged comments about her lack of children.
“I am honoured and humbled to have been chosen by the Conservative Party to become its leader,” said May, who favoured remaining in the EU but has made clear there is no going back.
“Brexit means Brexit, and we’re going to make a success of it,” she said on Monday.
Read more: Theresa May: Brexit means Brexit and it will be a success
Earlier, Cameron told reporters in front of 10 Downing Street that he expected to chair his last cabinet meeting on Tuesday and take questions in parliament on Wednesday before tendering his resignation to Queen Elizabeth.
“We will have a new prime minister in that building behind me by Wednesday evening,” he said.
May will become Britain’s second female PM after Margaret Thatcher. Her victory means that the complex process of extricating Britain from the EU will be led by someone from the losing side of the referendum.
She has said Britain needs time to work out its negotiating strategy.
In a speech earlier on Monday in the central city of Birmingham, May said there could be no second referendum and no attempt to rejoin the EU by the back door. “As prime minister, I will make sure that we leave the European Union,” she said.