As the repercussions from the Downing Street party controversy continue to weaken Boris Johnson's grip on power, four of his key staff members resigned.

Munira Mirza, Johnson's long-serving policy adviser, was the first to resign, accusing the PM of "scurrilous" behavior when he deceitfully linked Labour leader Keir Starmer to the failure to bring pedophile Jimmy Savile to justice.

Dan Rosenfield, Johnson's chief of staff, Martin Reynolds, his senior private secretary, and Jack Doyle, Johnson's head of communications, had resigned within hours.

All three have been linked to Downing Street's response to the lockdown parties -dubbed "partygate"- which the Metropolitan Police are currently investigating.

Reynolds issued a widely circulated email inviting employees to "bring your own booze" to a May 2020 gathering.

While many of Johnson's senior officials were anticipated to be sacked after Sue Gray's report on the lockdown-breaking gatherings was released earlier this week, Mirza's resignation came as a complete surprise.

Furthermore, in an indication of Johnson's weakening authority, the chancellor responded with a rare rebuke, criticizing the PM for his remark about the Labour leader.

At a news conference on Thursday, Sunak was asked about the remarks and stated, "To be honest, I wouldn't have said that."

When asked if Johnson should apologize, he replied it was up to the PM to decide.

Throughout the weeks of reports about lockdown-busting parties in Downing Street, Sunak has avoided publicly criticizing Johnson, though he has admitted that "mistakes were made."

The flurry of resignations occurred at the conclusion of a crucial day for the government, as the chancellor attempted to explain how he plans to avoid a cost-of-living catastrophe for millions of people whose fuel bills and mortgage payments are rising.

When Mirza left, the spotlight shifted back to the turmoil in Downing Street.

After claiming in a raucous House of Commons session on Monday that Starmer, as director of public prosecutions from 2008 to 2013, "spent much of his time pursuing journalists and failing to charge Jimmy Savile," Johnson has constantly refused to apologize.

In fact, Starmer played no part in the decisions relating to Savile's case.

In a resignation letter, Mirza told Johnson: “There was no fair or reasonable basis for that assertion. This was not the usual cut and thrust of politics; it was an inappropriate and partisan reference to a horrendous case of child sexual abuse.”

At Westminster, Mirza's resignation was seen as a major setback for Johnson, who was under pressure to restructure his Downing Street operation after Gray found leadership and judgment flaws.

It was quickly followed by Doyle's resignation later that day, but he stated his departure had nothing to do with Mirza's. Doyle "made a big contribution," according to a No 10 spokesperson, and "the prime minister is enormously thankful for the job he has done."

In a later statement, Downing Street affirmed Rosenfield and Reynolds' departures.

On Thursday, Johnson attempted to distance himself from the Savile allegations, stating that "a lot of people have got very hot under the collar."

However, this was insufficient to appease Mirza. She wrote in her resignation letter: “You tried to clarify your position today but, despite my urging, you did not apologize for the misleading impression you gave.”

She added Johnson was “a better man than many of your detractors will ever understand”, stressing that it was “so desperately sad that you let yourself down by making a scurrilous accusation against the leader of the opposition”.

Johnson wasted no time to replace Mirza, moving Andrew Griffith to Cabinet Office minister and head of the No 10 policy team.

Mirza's departure, according to Johnson's former aide Dominic Cummings, is “an unmistakable signal the bunker is collapsing and this PM is finished”.

Another indicator of the pressures on Johnson from within his own party comes from West Midlands mayor Andy Street, one of the most prominent Tories outside of Westminster, who said he was doubtful whether he could continue to back the PM.

On Wednesday, three new Conservative MPs announced their intention to write letters of no confidence: After popular and political trust in Johnson dramatically declined, his premiership is bound to be terminated if he loses the upcoming no confidence vote - which might be occurring within days.