Boris Johnson's leadership is hanging by a thread after the resignations of two of his most high-profile ministers and several other top officials.
Sunak said the government should be run properly and seriously. Health Secretary Sajid Javid resigned in protest of Johnson's leadership which has been beset by controversy and scandal.
As a number of senior Conservatives called for the prime minister to step down, the government's former negotiator David Frost also called for him to go. In a newspaper column on Wednesday, Frost said that it was time for Johnson to leave and that he risked taking the government down with him.
The prime minister doesn't seem to be ready to step down. The vacancies created by the resignations were filled by a new team of ministers.
Several ministers expressed their support for Johnson. Home Secretary Priti Patel is one of the top cabinet members.
The immediate prospect of a snap election is diminished by the loyalty of top ministers. Johnson would have to either resign or face a confidence vote. A new challenge would need to be made in order to allow another vote within the next year.
Johnson can't face another no-confidence vote until next summer. Allan Monks, an economist at JP Morgan, said in a note Tuesday night that the main risk is that the rules will be changed to force another vote or that Johnson will be pressured to step down.
There is a chance that a new Prime Minister could be in place before the party's annual conference in October.
The U.K.'s political instability caused sterling to fall to a new March 2020 low. Markets will be watched closely in the next few days.
Ben Emons, managing director of Global Macro Strategy at at Medley Global Advisors, told CNBC that there was a lot of uncertainty over how it would play out.
As sterling and U.K. gilt yields fell, the markets responded negatively, but then they recovered and I think that shows that he still has support.
The markets take some comfort in the fact that we are going to enter a period of uncertainty but that uncertainty reflects the status quo.
The latest political upheaval to hit the U.K. comes after a series of scandals, ranging from the "partygate" scandal with Johnson and multiple other government officials, to sleaze allegations, the latest of which involves Chris Pincher.
Pincher was suspended from the Conservative Party after he was accused of drunkenly groped two men. He was appointed to the role despite the fact that he had been accused of sexual harassment.
It was too late for Johnson to apologize for appointing Pincher as deputy chief whip.
Johnson has survived a number of challenges to his leadership in recent months, as well as calls for him to resign, particularly following a bruised confidence vote and the Conservative Party's loss of two key by-elections in the last month.
A majority of Britons want Johnson to resign, according to a poll. Only 18% of adults think he should stay on.
More than half of the Conservative voters surveyed want Johnson to go and less than one third want him to stay on.
Keir Starmer, leader of the Labour Party in Britain, said on Tuesday that changing one man won't fix the corrupted Tories. A change of government is what Britain needs.
The leader of the Liberal Democrats said that it was clear that the team in government was the one that would deliver.
It's damaging to Britain's reputation around the world and it's also damaging to our investment if we have a prime minister who doesn't tell the truth. The government needs to know what it's doing.
Johnson has been accused of lying multiple times during his time in office, though he has always denied doing so, and has denied misleading parliament over the "partygate" scandal.