Conservative leadership hopefuls will be named and shamed by party chiefs if they abuse rivals as the Tories seek to avoid all-out civil war.
Six senior Tories will battle it out to replace Rishi Sunak as the Conservative Party seeks to rebuild after its worst-ever general election result, with the new leader named on November 2.
Shadow housing secretary Kemi Badenoch is the early favourite with bookmakers, while former immigration minister Robert Jenrick looks set to challenge her on the Tory right.
Shadow security minister Tom Tugendhat and shadow home secretary James Cleverly look set to compete for votes from centrist Conservatives.
Former home secretary Dame Priti Patel and shadow work and pensions secretary Mel Stride complete the field of candidates who received the support of 10 MPs in order to enter the race.
Bob Blackman, chairman of the backbench Conservative 1922 Committee which is organising the contest, has introduced a “yellow card” system to issue warnings to campaigns if they cross the line in attacks on rival candidates.
He said: “The situation with the yellow card is very simple.
“The constant backbiting and attacking colleagues both in public and on the media in the last parliament was one of the contributory reasons as to why the party did so badly in the general election.
“We are determined that we will not tolerate that happening.
“So if candidates indulge in it, then I will get involved, obviously, to warn them and, if necessary, issue a public statement to the fact that they have been involved in such activity.
“If MPs get involved in such backbiting then the chief whip will intervene, and if ex-MPs get involved then the party chairman will be involved in making sure that simple action is taken.”
Mr Blackman added that a public statement about bad behaviour would be “extremely detrimental” to a candidate’s chances.
He added: “There’s a difference between vigorous debate and then attacking other individuals just because they happen to dislike what they are proposing.”
MPs will vote off two of the contenders in September so the final four go to the party’s conference in Birmingham to make their leadership pitch.
Conservative MPs will then eliminate two more, with the final pair going to a ballot of Tory members with the winner announced on November 2.
The backbench 1922 Committee confirmed the six candidates after nominations closed on Monday afternoon.
The party faces the twin challenges of responding to the threat from Nigel Farage’s Reform UK on the right, as well as winning back former heartlands in southern England which shifted to the Liberal Democrats.
Ms Badenoch was the last to publicly confirm she would stand, using a Times article to blame an “incoherent” set of policies for the party’s election drubbing.
The shadow housing secretary accused successive Conservative prime ministers of allowing Britain to become “increasingly liberal” and tolerating “nasty identity politics”.
“We talked right yet governed left,” she said.
