MPs are seeking to block new rules that could see them punished for indiscretions in their private lives.
A revised Code of Conduct being considered tomorrow states that politicians should not do anything that would "cause significant damage to the reputation and integrity of the House of Commons".
However, a cross-party group has tabled an amendment amid fears that individuals could be censured or even suspended for actions that have no bearing on their duties.
The MPs - including Tory 1922 committee chairman Graham Brady and former Liberal Democrat leader Sir Menzies Campbell - want to add a line specifying that the standards commissioner "may not investigate a specific matter under paragraph 16 which relates only to the conduct of a Member in their private and personal lives".
As well as the new Code of Conduct, MPs are due to consider changes that would see the public help investigate allegations of wrongdoing.
The plans would create a Standards Committee made up of 10 MPs and two or three lay members, who would be approved by the whole House.
However, the motion put forward by Leader of the House Sir George Young makes clear that the members of the public will not be able to decide on punishments.
"Lay members may take part in proceedings of the committee and of any sub-committee to which they are appointed and may ask questions of witnesses, but lay members may not move any motion or any amendment to any motion or draft report, and may not vote," it states.
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