Rebel Conservative MPs say they expect a censorship vote on Boris Johnson to be held in the coming days.
Letters expressing distrust of the Prime Minister must be submitted by 54 Conservative MPs to provoke a challenge.
Data collected by Sky News show that 28 Conservatives have publicly called for Mr Johnson’s resignation, and many more are questioning his position.
Business Minister Paul Scully also said on Sunday evening that “there could be” a vote of confidence, but predicted that the prime minister would “face” this challenge.
The process of triggering a vote is anonymous, and only the great MP Sir Graham Brady, who chairs the 1922 Conservative Committee, knows who sent a letter.
A rebel MP told Sky News that they suspected the vote would take place this week, but added that it was difficult to know precisely because it was a show of “organic and completely disorganized” concern from MPs.
Earlier this year, suggestions for an imminent leadership challenge did not materialize and a MP who sent a letter warned that “anything could happen” in the coming days.
There have been suggestions that the vote should be postponed to the end of the month to maximize the chances of removing the prime minister.
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“Boris is not going anywhere”
A senior MP who has called for Mr Johnson’s resignation said having a vote now would be “silly” and “too risky”.
If a contest is triggered, 180 Conservative MPs would have to vote against the Prime Minister for his removal.
Johnson’s allies said he would win the vote whenever he arrived, a year of immunity from a new challenge, according to party rules.
“After 12 months, we will be very close to a general election, so we are probably very reluctant to withdraw it then … Boris is not going anywhere and will take us to the next general election,” said a former solidarity minister. .
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“Conservatives are unlikely to win the next election”
Downing Street will try to focus on domestic politics this week, with a series of announcements about the NHS and a possible speech on housing construction.
However, a poll on Sunday predicted more problems for the prime minister, predicting a big loss in the Wakefield by-elections later this month.
“The main reason voters give is that Boris Johnson slammed the party door and then lied about it,” said James Johnson, a JL Partners pollster.
“The second biggest reason is that Boris Johnson is out of touch with working class people.”
Activists have also criticized the prime minister, with Conservative group chairman Ed Costelloe telling Sky News that Johnson should “go with dignity” in the coming months.
“If he stays as prime minister, it is very unlikely that the party will win the next election, which would mean a kind of coalition of Labor, Lib Dems and SNP,” Costelloe said.