In the row over events at No 10 during lockdown, former minister Nick Gibb has written a letter of no confidence. Meanwhile, Conservative MP Stephen Hammond said he was "considering very carefully" whether he had confidence in David Cameron.
According to Culture Secretary Nadine Dorries, MPs backed Mr Johnson by a "vast majority." Meanwhile, a photo of Mr Johnson holding a beer at a birthday gathering was shared with police looking into the matter.
In an article written by the Daily Mail, it said the picture was one of 300 submitted as part of an investigation by the Metropolitan Police into 12 alleged gatherings and was likely taken by the PM's official photographer.
A picture was posted on social media that showed the prime minister holding a can of beer at a June 2020 event in No 10's Cabinet Room alongside Chancellor Rishi Sunak holding a soft drink.
In those days, gatherings of more than two people inside were illegal.
The PM has had an extremely difficult week, in which five No 10 aides quit and the initial findings of the Sue Gray report into events at Downing Street while there were Covid restrictions have been released.
He told the Daily Telegraph that his constituents are "furious about the double standards," and that "to restore trust" he will return to his former post as schools minister, which he lost in Boris Johnson's reshuffle last September.
"Flagrant disregard" was shown to Covid restrictions imposed by Mr Johnson in Downing Street, he said, and the PM was in error when he told the House of Commons in December that there was no party.
"Some argue that a few canapes with wine is not a sufficient reason to resign. But speaking the truth is paramount, and wherever truth must be told, a court of law must do the same." he wrote.
Stephen Hammond, Conservative MP for Wimbledon, told the BBC Radio 4's Week in Westminster programme: "I think all Conservative colleagues, all of whom I know, are in it for trying to do the best for their constituents, and the country will be wrestling with their consciences this weekend."