Conservative candidates hoping to replace Prime Minister Theresa May will face at least a dozen hustings before a winner is crowned.
The 1922 Committee of Tory backbenchers have laid out the leadership contest rules that will whittle down the 11 current candidates to two.
After a series of MP ballots, the final two competitors will go into a run-off decided by the party’s 160,000 membership.
Joint acting chairman of the 1922 Committee, Charles Walker, said he is “aiming to have two people” by June 20.
“Who knows? We might finish this process before Thursday June 20,” he said.
Mr Walker doubts there will be a repeat of 2016, when Andrea Leadsom withdrew from the race to allow a clean handover from David Cameron to Mrs May.
“The expectation is that if they are in the final two, they will go through and put themselves before the membership through the membership hustings,” he said.
“I think there is great recognition across the parliamentary party that this does need to go to the membership this time.”
Security will be tight during the voting process.
All ballot papers will be stamped by the 1922 Committee's officers, and the colour of the papers will only be decided the night before voting.
MPs will not be allowed to take pictures of their ballot papers when they vote in a committee room in the Palace of Westminster.
Mr Walker said MPs will be required to carry their parliamentary passes “which they hate doing”.
Mrs May will resign on Friday, but will stay on as acting Prime Minister until her replacement is appointed.