A leadership contest can be triggered in two ways: If 15 per cent of Conservative MPs write to the chairman of the 1922 Committee expressing they no longer have confidence in the party leader, or if the current leader resigns.
"Theresa May will remain as Acting leader of the Conservative and Unionist Party until her successor has been announced", the press release specifies.
The final two candidates will be put to a postal ballot of about 160,000 Conservative members, with the victor announced the week of July 22.
Brexit Party leader Nigel Farage reacts after the European Parliament election results for the UK South East Region are announced at the Civic Centre Southampton, Southern England, on May 26, 2019.
In the 2016 referendum, 52 percent of voters chose to leave the European Union, while 48 percent wanted to remain.
She spent the day in her constituency west of London.
It leads to the resignations of Brexit Secretary David Davis, Foreign Secretary Boris Johnson and others who favour a more complete break with the EU.
Labour hailed a slim victory by Lisa Forbes, who won 10,484 votes, beating the bookmakers' favourite, the Brexit Party, into second with 9,801 votes.
Nearly a dozen Conservative lawmakers are already jostling to replace May in a contest that formally opens Monday, vowing to succeed where she failed and renegotiate Britain's divorce deal with the European Union.
MPs backed the process for leaving the bloc by triggering Article 50 to end Britain's membership on March 29.
The process to find May's successor starts on Monday, although the race for the top job in British politics has kicked off with 11 contenders throwing their hats into the ring.
Boris Johnson, the frontrunner to replace May, said the rise of the Brexit Party could open the door to a Corbyn government.
Candidates from the 313 Conservative MPs will require a proposer, a seconder and six other MPs to support their candidacy to continue to the first ballot.
May formally relinquished her leadership in the private letter to her party on Friday.
Health secretary Matt Hancock said the defeat showed the Tories should be more concerned about Labour, not the Brexit Party.
"The EU didn't regard itself as negotiating with the transient British Prime Minister, it regarded itself as negotiating with the United Kingdom government", added Rutter.
As they rally support for their campaigns, Conservative prime minster candidates have been circling around three options: Ignore the Withdrawal Agreement, renegotiate it, or ask parliament again to ratify it unchanged.
But for the governing Conservatives, the fierce challenge by the Brexit Party, which only launched in April, will encourage contenders hoping to replace Mrs May to stick to a tough message on Britain's exit from the EU.
The front-runner, Boris Johnson, has warned the Conservatives face "extinction" if Britain doesn't leave the European Union on October 31.
Despite its emphatic vote for Brexit, the Cambridgeshire town voted for Jeremy Corbyn's Labour in parliamentary elections the following year, displacing its leave supporting Conservative MP. "I think they are the really big losers here", he added.