Mid Norfolk's Tory MP has called for the Prime Minister to resign - as rumours of a coup to oust her step up.
George Freeman says there is a "constitutional crisis" and a new leader is needed to break the gridlock over Brexit.
He is backing the Environment Secretary Michael Gove to take over.
It comes as speculation that Theresa May will be ousted from Number 10 ramped up. There are reports cabinet ministers are plotting a coup to get rid of her.
The Sunday Times reported 11 Cabinet ministers had told the paper they wanted Mrs May to make way for someone else and that the PM's de facto deputy David Lidington, who is the MP for Aylesbury, was in line to take over the helm.
But the Mail on Sunday reported ministers were plotting to install Environment Secretary Michael Gove as a caretaker leader.
On Saturday, around one million people were said by organisers to have joined a march on Parliament demanding a final say for the public over Brexit.
Marchers waving EU flags and carrying their placards emblazoned with political messages weaved their way from Hyde Park Corner to Parliament Square.
Elsewhere, pro-Brexit campaigners will continue their long hike from the North East to the capital, leaving Loughborough on Sunday morning.