Boris Johnson's right-hand man Dominic Cummings has left Downing Street after a power struggle that has rocked the prime minister's administration.
Mr Johnson's senior advisor exited Number 10 carrying a large box on Friday evening following a bitter dispute which also led to the resignation of Mr Cummings' fellow Vote Leave veteran Lee Cain as communications chief.
The dramatic events come ahead of crucial Brexit talks with Brussels with the transition period deadline of 31 December looming.
Sky presenter Sophy Ridge said: "It is incredible to take a step back and think that at such a critical moment - a week that could have profound consequences for the future of the UK and Europe - the prime minister has lost two of his most important aides and been distracted by one of the most vicious Downing Street battles that Westminster watchers can remember.
"What's clear is that this marks a pivotal moment for Boris Johnson.
"The battle of the last week has seen the old guard burned to the ground - what we don't know is what will emerge from the ashes."
Meanwhile, The Sun reported there was a "shouty" confrontation between Mr Johnson and Mr Cummings over the ousting of Mr Cain and that a "livid" prime minister wanted both out "sooner rather than later".
Some reports suggested Mr Cummings has quit his post with immediate effect, while others suggest he and Mr Cain will be employed until mid-December.
A number of Conservative backbenchers have urged Number 10 to use this as an opportunity to restore several important values within the party.
Senior Tory MP Sir Bernard Jenkin said it was time to restore "respect, integrity and trust" to the relationship, elements which had been "lacking in recent months".
The Daily Telegraph said tensions within Number 10 were running high, with Mr Cummings accused of briefing against the prime minister.
The newspaper reported Mr Cummings was said to have told colleagues Mr Johnson was "indecisive" and that he and Mr Cain relied on Cabinet Office minister Michael Gove for clarity.
It was also suggested the PM was angered by claims a faction headed by Mr Cummings and Mr Cain had been "briefing against him" and his fiancee Carrie Symonds.
Meanwhile, shadow health secretary Jonathan Ashworth highlighted the strain being heaped on the NHS and the public by COVID-19 while "Downing Street is paralysed by the soap opera of these self-indulgent spin doctors".
The prime minister's official spokesman, James Slack, who will replace Mr Cain in the new year, insisted Mr Johnson is not being distracted from the national crisis by the row.
"What the prime minister and the government are focused upon is taking every possible step to get this country through the coronavirus pandemic," he said.