Chief Whip Andrew Mitchell could face a humiliating House of Commons vote on his confrontation with police as he struggles to keep his job.
Labour is tabling a motion calling for Mr Mitchell to be docked £1,000 from his salary - roughly the same amount he could have been fined for swearing at an officer.
Pressure on the embattled Government enforcer shows little sign of abating, nearly a month after news broke of his clash.
Opposition MPs are promising to take full advantage of a prospective first appearance alongside David Cameron at Prime Minister's Questions on Wednesday. There is also speculation that his support among Cabinet colleagues and the Tory rank-and-file is softening.
Mr Mitchell has denied calling officers "plebs" after they refused to let him cycle through the main gates at Downing Street on September 19. However, he has conceded that he swore and did not show enough respect.
Under Section 5 of the Public Order Act anyone convicted of a public order offence can be fined between 50% and 125% of their weekly income by magistrates. As Mr Mitchell earns around £79,000 per annum from his Government role, Labour is demanding that he gives up £1,000.
A senior party source said: "If David Cameron is not going to act on Andrew Mitchell's mess, then Parliament should."
However, it is far from clear that Labour will be able to force a vote on the issue. As chief whip, Mr Mitchell himself plays a part in deciding what votes are held.
A Downing Street spokeswoman declined to comment on the motion about Mr Mitchell's pay.
She told a regular daily media briefing in Westminster: "The Prime Minister has been very clear on this issue from the start. Andrew Mitchell behaved in a way that he shouldn't have towards a police officer, but he has apologised to that police officer and that apology has been accepted. The police do a very difficult, demanding job and we are very clear about the support we give to the police and the Prime Minister made a statement at the time acknowledging the fine work our police officers do."