Tory bosses warn leadership candidates to stay in race to avoid Boris Johnson coronation
Tory leadership candidates have been warned not to drop out of the race if they make it through to the final ballot.
Party bosses took the unusual step amid claims some of those running would rather quit than face a run-off against bookies' favourite Boris Johnson.
Theresa May was elected unopposed in 2016 after Andrea Leadsom pulled out despite making it through to the final stage of the contest.
Charles Walker, acting joint-chair of the 1922 Committee of Tory backbenchers, said the 11 candidates who have so far indicated they plan to run were told at a special meeting that there must not be a repeat this time round.
He said: "The expectation is that if they are in the final two, they will put themselves through the membership hustings."
Mr Walker added: "We've had a conversation with those who have indicated they are going to put their papers in.
"There is a great recognition across the parliamentary party that this does need to go to the membership this time. Potential candidates are fully aware of that and hopefully relishing the prospect."
Rory Stewart, one of the outsiders in the contest, said he would not pull out of the race - and challenged his rivals to make the same pledge.
It has also emerged that Conservative officials are going to extraordinary lengths to make sure there is no cheating in the contest.
Differently coloured ballot papers are being printed for each round of voting by MPs, with the colours only being decided the night before to avoid any chance of forgery.
All MPs will have to have their parliamentary security pass with them when they vote or they will be turned away.
Theresa May formally stands down as Tory leader on Friday, with nominations for her successor closing on 10 June.
Hustings will take place on 11 and 12 June, with the first round of voting by MPs taking place the day after.
Following a hustings involving the remaining candidates on 17 June, the second ballot will take place on 18 June.
Up to five MPs ballots are expected to take place, with the last two candidates standing announced on 20 June. They will then go forward to a ballot of Tory Party members, with the winner expected to be announced by 22 July.