Ps will try to oust Nadine Dorries as an MP next month amid growing calls for her to follow through on her vow to resign.
The Liberal Democrats will table a Bill when Parliament returns on September 4 that they hope will result in her suspension.
The Tory former minister has angered voters, opposition MPs and some in her own party by remaining in post since she said in June she would leave her parliamentary seat with “immediate effect” in protest at not getting a peerage in Boris Johnson’s resignation honours list.
Ms Dorries – whose claim that Prime Minister Rishi Sunak removed her peerage nomination has been denied by Downing Street – said she is delaying her exit while she investigates why she was refused a seat in the Lords.
The Lib Dems on Friday said deputy leader Daisy Cooper will lay down a motion demanding Ms Dorries returns to the House of Commons by September 14 or face a 10-day suspension.
If MPs approve it, a recall petition will be triggered in Ms Dorries’ seat.
This would pave the way for a by-election if more than 10% of constituents sign it.
Ms Cooper said: “For months Nadine Dorries has treated the people of Mid Bedfordshire with contempt and taken them for granted.
“As thousands of people struggle to get a GP appointment and face steep hikes to their mortgages, Nadine Dorries continues to be missing in action. What’s worse is that the Conservatives just don’t seem to care that they’re letting people down.
“We need an end to this sorry saga, once and for all. Nadine Dorries must resign. If not then this Government must do the right thing and force her to. Every day that Rishi Sunak sits on his hands the people across Mid Bedfordshire are being failed.”
The Prime Minister said at the beginning of the month that Ms Dorries’ constituents were not being properly represented, but although a number of Tory MPs have since spoken out against her, she retains the Conservative whip.
Labour, the Lib Dems and two town councils in her constituency – Shefford and Flitwick – have urged her to go.
John Penrose became the latest Tory figure to voice their frustration at her refusal to step aside, having promised to do so.
The former Conservative Party whip told Times Radio: “If she’s going to stay she should stay, if she’s going to go she should go.
“She needs to make sure everybody who voted for her and who she represents knows what she’s doing.”
Fellow Tory MP Tom Hunt earlier accused her of showing “extraordinary” entitlement for failing to formally quit.
In a brief statement on Tuesday, Ms Dorries insisted she and her staff “are working daily with constituents”.
The ex-culture secretary and close ally of former prime minister Mr Johnson has not spoken in the Commons since June 2022 and last voted in April.
Ms Dorries and No 10 have been contacted for comment.