A Tory MP has reportedly submitted a letter calling for Liz Truss to face a vote of confidence as a backbench rebellion begins against the under-fire PM.
The unnamed member of the parliamentary Conservative party told Bloomberg political editor Kitty Donaldson that they had handed in their letter to the 1922 committee on Sunday night.
While Tory MPs say letters have been going in for more than a week, this may be the first report of an MP personally admitting they have sent one themself.
Current rules give Liz Truss until next September before she can be ousted - but these could be changed by MPs.
The intervention less than a month into her premiership comes after her chancellor's mini-budget announcement resulted in a financial crisis, which saw the pound tumble and several pension funds left just hours away from insolvency.
Liz Truss, who yesterday admitted Number 10 should've "laid the ground" better before unveiling the sharp rise in public borrowing, now faces the challenge of winning over angry backbenchers at this week's Tory conference.
Under pressure to mount a U-turn, she could now delay the vote on cutting the 45% rate of tax, The Telegraph reported on Sunday citing government sources.
The Tories have seen their public approval ratings collapse since Kwasi Kwarteng's tax-cutting package, with one YouGov poll putting them at just 21% among the UK electorate - a whole 33 points behind Kier Starmer's Labour.
Members are said to fear that the party may lose credibility on managing the economy for a generation, with polling showing the Tories also falling behind the opposition on economic competency.
Talk of a rebellion has increased as party members gather in Birmingham, with grandee Michael Gove yesterday attacking Liz Truss's tax cuts for the richest Brits as a "display of the wrong values" during the cost of living crisis.
Speaking on the BBC's Sunday with Laura Kuenssberg, Mr Gove said the PM was right to acknowledge that the events of the mini-Budget "need to be revisited".
"But it is still the case that there is an inadequate realisation at the top of government about the scale of change required," he said.
"Yes, the energy package was the most important thing in the fiscal event, but broadly 35% of the additional money that we are borrowing is not to cut energy costs, it is for unfunded tax cuts."
He added: "There are two major things that are problematic with the fiscal event. The first is the sheer risk of using borrowed money to fund tax cuts - that is not Conservative.
The former cabinet minister also repeatedly declined to say whether he would vote for the measures in Parliament - but said he was "profoundly concerned".
Former transport secretary Grant Shapps has joined the Tory revolt against Liz Truss’s tax plans, calling her decision to scrap the 45p top rate "politically tin-eared"
Predicting she would lose the vote in the House of Commons, he accused the Prime Minister and Chancellor Kwasi Kwarteng of putting “all their chips on red” in the hope that cutting taxes will deliver growth.
Liz Truss is expected to address the Conservative Party conference at the ICC in Birmingham on Wednesday morning.
