Former Tory whip Chris Pincher has lost his appeal against an eight-week suspension from the House of Commons following allegations he drunkenly groped two men at London’s exclusive Carlton Club last year.
The suspension exceeds the 10-day threshold that would trigger a recall petition in his Tamworth seat if MPs approve it.
This could pave the way for a by-election if more than 10% of constituents sign it.
The Commons Standards Committee in July recommended a lengthy suspension for Mr Pincher after it found the MP’s conduct last summer was “profoundly damaging” and amounted to an abuse of power.
His actions were described as “unwanted, inappropriate and upsetting”, in what amounted to an “egregious case of sexual misconduct”.
Boris Johnson’s handling of the row over his former chief whip was the final nail in the coffin of his premiership, triggering his resignation last year after an exodus of ministers from his administration.
Mr Pincher, who remains MP for Tamworth, lodged an appeal against the committee’s findings arguing it was disproportionate.
However, Parliament’s watchdog, the Independent Expert Panel (IEP), on Monday dismissed his appeal and upheld the Standards Committee’s recommended sanction.
The IEP’s report said: “We consider that the appellant’s arguments are misconceived or erroneous. The sanction is far from being arbitrary or disproportionate.”
Mr Pincher did not appeal against the Standards Committee’s conclusion that he had broken the MPs’ code of conduct by behaving in a way that would cause “significant damage to the reputation and integrity” of the Commons.
But he argued in his appeal submission that his behaviour had not damaged Parliament’s reputation as he had spoken at the private members club as a minister rather than as an MP.
He resigned as a Government whip after the incident and subsequently lost the Tory whip, meaning he now sits in the Commons as an independent.
Mr Pincher, who has already indicated he will not seek re-election, could choose to stand down as an MP following the appeal decision, which would automatically trigger a contest in his Staffordshire constituency.
Downing Street refused to be drawn on whether Mr Pincher should quit the Commons and said it was a matter for him.
His suspension could leave Rishi Sunak facing a tricky double by-election as the Conservatives languish in the national polls.
Former culture secretary Nadine Dorries’ bitter exit last week means one is set to take place this autumn in her Mid Bedfordshire seat.
Mr Pincher has been comfortably voted for by Tamworth residents since 2010, and he won a 19,634 vote majority at the last general election.