A furious MP tonight became the third member of the Tory Parliamentary group calling for Liz Truss to go - accusing her of damanging the economy and stoking hatred towards transgender people.
Jamie Wallis, MP for Bridgend, joined Crispin Blunt and Andrew Bridgen demanding the PM steps down just 40 days into her time in the top job.
Dr Wallis, who in March became the first ever MP to announce they were trans, lashed out at Ms Truss for failing to stand up to senior colleagues scoring "cheap political points".
The MP accused Ms Truss of packing the cabinet with loyalists, accusing her of "very basic and avoidable errors".
Dr Wallis wrote: "Your decision to appoint historical supporters of you personally rather than the most qualified politicians available in the party has led to decisions that have done clear and obvious harm to the British economy.
"Furthermore, they have undermined Britain's credibility as a trustworthy, responsible leading economy, and fractured our party in a potentially irreparable manner."
The scathing letter went on to accuse the Prime Minister of allowing party members to "exploit" transgender rights.
Dr Wallis stated: "Watching senior colleagues exploit the issue of transgender rights and weaponise it in order to score cheap political points was extremely unpleasant.
"But observing the hostile nature of the debate and then witnessing hostility towards transgender people on social media and in-person was distressing. However, you chose not to challenge this behaviour and have now chosen to have those same colleagues sit alongside you in your government."
Although he did not mention any names, it comes on a day Home Secretary Suella Braverman hit out at a police force which tweeted about transgender abuse being a hate crime.
Ms Braverman said that she would make police chiefs who use resources for "politically correct campaigns" explain themselves.
Earlier today Leicestershire Police shared a post featuring a woman named Jane, who said she was deliberately referred to by her previous male name - which she described as "hurtful".
Ms Braverman responded: "The police need to enforce actual laws & fight actual crimes. Freedom of speech must be protected and a proportionate approach must be taken.
"The public need to have confidence in their police forces. This sort of thing undermines it. Senior police officers who allow this to happen can expect to have to explain to me why they’re spending vital resources on politically correct campaigns."
The Tory MP said appointing an English MP as Secretary of State for Wales and her dismal handling of the press made it clear Ms Truss could no longer lead a united party.
Dr Wallis wrote: "Therefore, I ask you to stand down as Prime Minister as you no longer hold the confidence of the country or the parliamentary party.
"It is the right thing to do to ensure the stability, security and prosperity of the people to whom we owe everything."
Ms Truss faces an increasingly difficult job to cling onto the top job after a dismal start.
Today Crispin Blunt, the Conservative MP for Reigate who was a justice minister in the early years of David Cameron's premiership, told Channel 4's Andrew Neil Show: "I think the game is up and it's now a question as to how the succession is managed."'
Mr Blunt, who backed Jeremy Hunt in the leadership contest, released a statement on Sunday in which he said that most of his colleagues "clearly understand that Prime Minister Truss's authority is now fatally damaged".
"She has to go now as she cannot win nor sustain the confidence of her colleagues, far less the public and a relentless media.
"The principal emotional reactions to her public presentation is now a mixture of anger, contempt and pity.
"It's a blinding glimpse of the obvious that this cannot and should not continue."
He called for former leadership contenders Mr Sunak, Mr Hunt and Penny Mordaunt to come together to steer the party out of the current crisis.
He was followed by Andrew Bridgen on Sunday evening, who told Telegraph newspaper: "We cannot carry on like this."
Mr Bridgen, who backed Rishi Sunak in the leadership contest over the summer, said: "Our country, its people and our party deserve better."