A majority (59.48%) of Tory members now believe Mrs May should resign, according to a snap survey by the Conservative Home website yesterday.
It found that just 36.66% of the 1,503 respondents believe she should stay on.
The survey had not been carried out as a weighted sample as people self-selected to vote in it.
Editor Paul Goodman said the results were "astonishing" and "the most damning finding that in one of our polls that I can remember".
Theresa May is expected to receive a frosty reception when she meets the 1922 Committee later. But what do we know about the group?
The Prime Minister appointed her former leadership rival as Environment Secretary as she confirms her new top team.
He insisted he would be backing Theresa May as leader and has warned MPs to "calm down and get behind the Prime Minister".