The tone has hardened within Johnson's own party after recent weeks' revelations about partying at the Prime Minister's residence during the pandemic.
Ahead of today's question time in the lower house, a dozen party members, who were appointed in 2019, have also met to discuss Johnson's political future, several British media report.
Letter of no confidence sent
The meeting, which took place on Tuesday evening, and which is called "Pork pie putsch", has received a lot of attention in the British media.
In order for Johnson to face a no-confidence motion, 54 party members, corresponding to 15 percent of Tories' lower house members, must send secret letters to the so-called 1922 committee and after the meeting 20 letters are said to have been sketched or sent in, reports The Guardian.
At present, Johnson is expected to lose such a vote, if it does.
However, the committee's chairman Graham Brady is the only one to know how many letters have been received.
The opposition within the party has been dismissed by the circle around Johnson as a Pork Pie Plot, "meat pie plot", as it is believed to be led by members from the parts of central England where such pie comes from.