There has been no good news for Boris Johnson today. After an email leaked on Monday evening showing that the Prime Minister’s Principal Private Secretary Martin Reynolds invited over 100 staff to a drinks party in the No. 10 garden in May 2020, the Prime Minister has come under fire from his own side. Downing Street has refused to deny reports that both Boris Johnson and his wife Carrie were present at the event. Instead, all No. 10 will say is that Sue Gray’s inquiry into alleged Covid rule breaking at various Downing Street parties is ongoing.

The atmosphere in the Commons has been notably muted. The Tory benches were rather quiet when Michael Ellis — Paymaster General — was sent to field an Urgent Question on the issue. A handful of MPs spoke in Johnson’s favour — but it’s not clear they helped him out much. The kindest defence was that MPs ought to wait until the official inquiry was completed before passing judgment. Michael Fabricant appeared on the airwaves with his own effort: playing down the drinks as a meeting between office workers who were seeing each other every day anyway.

However, mainstream opinion is turning against Johnson. Some have been vocal — Scottish Conservative leader Douglas Ross has said Johnson must quit if he broke lockdown rules, and former minister Johnny Mercer has described the situation as ‘humiliating’. The Tory donor John Caudwell has called on the Prime Minister to:

Sort it out, Boris, or step aside and let someone else sort it out so that the Tories aren’t wiped out at the next election.

A poll by SavantaComRes says 66 per cent of those surveyed say the Prime Minister should resign over ‘partygate’.

Crucially, behind the scenes the mood in the parliamentary party is starting to turn against the Prime Minister. Many MPs and ministers have spent the day sounding out colleagues as to how bad things really are. The hope had been that the worst of the row was in December, but the new revelation has meant the row is once again dominating the news agenda.

The conclusion even Johnson’s natural supporters are coming to is that there is no card for him to play to make the issue go away. ‘I can’t see a way out for him,’ says one senior Tory. If Johnson did attend the event, it’s hard to see how he can justify it. Even if Johnson apologises now, it could be seen as too little, too late.

MPs are pointing to Prime Minister’s Questions on Wednesday as a pivotal moment where Starmer will no doubt zone in on Johnson’s involvement. So far neither Downing Street nor Johnson will deny that he attended the event. If he admits to this in the chamber, it could solidify concerns among MPs. But if he refuses to say whether or not he was there, he risks looking absurd.

Tory MPs today have been talking about Johnson’s departure more as a matter of when, not if. The best thing going for Johnson right now is that many MPs are unconvinced by the potential successors — with Rishi Sunak and Liz Truss viewed as the frontrunners — so would rather stick to what they know for now. But it’s hard to see how Gray’s partygate report can absolve Johnson of responsibility. As an experienced civil servant, Gray will not want to be accused of a whitewash.

While the local elections in May have been cited as a critical moment, MPs are beginning to ask whether Johnson could simply choose to go. ‘I think there is a one in five chance he walks,’ says an MP who backed Johnson for leader.