Three Tory MPs have stepped down from a committee set up by under-fire speaker John Bercow to improve 'inclusion' in Westmisnter.
The Speaker's Office said Will Quince, Mims Davies and Anne Milton had resigned from the Commons Reference Group on Representation and Inclusion, which is responsible for investigating complaints.
The three quit saying he is not the right person to resolve the "numerous and serious issues" around bullying in parliament.
Mr Bercow is himself at the centre of numerous allegations of bullying by Commons staff - all of which he denies.
Mr Quince said he did not believe Mr Bercow was the right person to handle the "numerous and serious issues" which had been raised about the conduct of some MPs and Commons staff.
However, in the light of the Dame Laura Cox report, sadly I cannot in good conscience remain as a member of the group while John Bercow is chair," he said.
"As much as I personally like John, I have reluctantly reached the conclusion that he is not the right person to resolve the numerous and serious issues."
Ms Davies said: "I felt that remaining on this (committee) currently did not sit right following Dame Laura Cox's report, and as this committee is chaired by the Speaker, I sadly felt in a difficult position. I did not take this decision lightly."
In a statement, a spokeswoman for the Speaker's Office said Mr Bercow had accepted their resignations "with regret" and paid tribute to them as "stellar members" of the group.
She said the Speaker would consider the group's future after the House of Commons Commission has met on Wednesday to consider Dame Laura's report.
A damning report by Dame Laura Cox QC highlighted a Westminster culture which allowed the bullying and sexual harassment of staff to flourish.
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The former High Court judge questioned whether the issue could be tackled successfully under the present Commons leadership - leading to calls for Mr Bercow to stand down.
Dame Laura was appointed to head an investigation after BBC Two's Newsnight highlighted claims of bullying of Commons staff by MPs and other staff, including Mr Bercow.
