Theresa May formally resigns, to act as PM until new Conservative leader elected

British Prime Minister Theresa May Friday formally resigned as the leader of the ruling Conservative Party, paving the way for a keen contest to decide a new premier who will take charge of the UK's tough divorce negotiations with the European Union.

May, who had stepped down amid mounting pressure over her repeatedly defeated Brexit deal, will continue as acting prime minister until the party has elected her successor, who will then take charge as the premier.

May, 62, handed in her private resignation letter to the backbench 1922 Committee, two weeks after announcing her intention to leave, the BBC reported.

The committee said it was now inviting nominations from those Conservative MPs "who wish to stand for election as the next party leader".

There are so far 11 hopefuls, including frontrunner Boris Johnson, the former foreign secretary. The other key contenders are foreign secretary Jeremy Hunt and environment secretary Michael Gove.

The winner of the contest is expected to be announced in the week of July 22.

The formal Tory voting process will be triggered on Monday morning.

"It is, and will always remain, a matter of deep regret to me that I have not been able to deliver Brexit," May, Britain's second female Prime Minister after Margaret Thatcher, said in her emotional speech on the steps of Downing Street on May 23.

"It will be for my successor to seek a way forward that honours the result of the referendum. To succeed, he or she will have to find consensus in parliament where I have not. Such a consensus can only be reached if those on all sides of the debate are willing to compromise," she said, indicating the tough road ahead for any new leader who steps into her shoes now.

May has been prime minister for nearly three years since she took over from David Cameron in the wake of the June 2016 Brexit referendum.

It will be business as usual for her for some weeks while the influential Committee goes through the leadership contest.

The leadership candidates need eight MPs to back them. Conservative Party MPs will then vote for their preferred candidates in a series of secret ballots held on June 13, 18, 19 and 20.

Charles Walker of the Conservative backbench 1922 Committee, which sets the rules of the contest, said: "We are aiming to have two people by Thursday 20 June."