The government is facing a third by-election test after disgraced ex Conservative MP Chris Pincher quit on Thursday.
The former Tory whip said he has "made arrangements to resign and leave the Commons" after losing his appeal against an eight-week suspension over groping allegations.
The Commons Standards Committee said he should face an eight week suspension in July following an investigation into the claims he caused "significant damage to the reputation of the House" by allegedly groping two men at the exclusive Carlton Club.
Mr Pincher - who resigned from Boris Johnson's government over the allegations last summer - did not appeal against the breach of the members' code, but argued that the punishment was disproportionate.
He lost the appeal and would have faced a recall petition in his Tamworth constituency had he not resigned.
The government will now face a by-election in the Staffordshire seat.
Elections are also taking place on October 5 in Nadine Dorries former constituency Mid Bedfordshire and in Rutherglen and Hamilton West in Scotland.