Nigel Evans should not step down as Commons Deputy Speaker over allegations of rape and sexual assault, former chief whip Andrew Mitchell said.
Mr Mitchell, who quit the Cabinet last year over disputed claims that he called police officers “plebs” – said it would set a “terrible” precedent.
Tory MP Mr Evans was arrested at his home and questioned by police on Saturday, but insists the claims by two young men are “completely false”.
He made clear through his solicitor that he intended to carry on as Deputy Speaker while police continue their investigation.
But Speaker John Bercow has agreed he be excused his duties chairing the week-long debate on the Queen’s Speech, which begins tomorrow.
Defence Secretary Philip Hammond questioned on Sunday whether Mr Evans could continue in his post while he was under investigation.
“I stick rigidly to the view that we should treat people as innocent until they are proven guilty, but it is quite difficult to carry out a sensitive and high-profile role while being under this kind of scrutiny,” he said.
But Mr Mitchell said: “If he were to resign now, we would be in a terrible position where every public office holder would be open to blackmail and false stories in the media, triggering their resignation.”
He went on: “Anyone who is caught up in the sort of intensive media storm which Nigel has faced is in a very difficult position to carry out their job,
“But I am in no doubt that Nigel Evans should not resign.
“He has not been charged, he has not been found guilty.”