British Prime Minister Boris Johnson should resign, a lawmaker in his Conservative Party said on Twitter, announcing he had submitted a letter of no confidence.
Johnson has so far weathered calls to quit over parties held in his Downing Street residence and office during coronavirus lockdowns.
"After a great deal of soul-searching, I have reached the conclusion that the Prime Minister should resign," said Peter Aldous, the Member of Parliament for Waveney, eastern England.
"I have never taken such action before and had hoped that I would not be put in such an invidious position. Whilst I am conscious that others will disagree with me, I believe that this is in the best interests of the country, the Government and the Conservative Party."
In order to trigger a leadership challenge, 54 of the 359 Conservative members of parliament must submit letters of no confidence. The number of letters currently submitted is not known but several have publicly said they have sent theirs.
A limited report by senior civil servant Sue Gray on Monday found that alcohol-fueled events had taken place at 10 Downing Street when rules banning all but limited social mixing were in force, and there had been "serious failures" of leadership.
