More Conservative MPs have voted no confidence in British Prime Minister Boris Johnson following the release of the report on banned lockdown parties during the coronavirus pandemic.

Johnson’s claim that he was unaware of the celebrations at Downing Street was “simply not credible,” said MP John Baron.

MP David Simmonds also called on the conservative head of government to resign. Earlier, MP Julian Sturdy Johnson had withdrawn his support. The number of opponents within the party rose to 18.

Johnson still seems relatively safe: In order to trigger a vote of no confidence in his own Tory party, 54 Conservative MPs have to withdraw their confidence. Johnson apologized after the full report was released on Wednesday. He ruled out resignation.

Johnson had previously been fined by police for attending a birthday party. However, he has yet to face a parliamentary inquiry into whether he lied to Parliament. He had long denied that there were illegal celebrations.