A defiant Boris Johnson has made it clear that he will not relinquish his grip on power, despite calls from Tory Party ministers and MPs for him to stand down.
No prime minister in modern history has tried to cling to office in the face of such overwhelming opposition from his own side.
It places the ball firmly in the court of those who believe their position has become untenable.
– What can be done to get Mr. Johnson out of number 10?
In the first instance, the focus will fall on the Cabinet.
So far, most of Johnson’s core team remain in their posts, even though Home Secretary Priti Patel and newly appointed Foreign Minister Nadhim Zahawi are among those who have asked him to leave.
Mass resignations by the Cabinet, accompanied by more resignations at lower levels, could be enough to force him down if it leaves him unable to form a functioning government.
However, there are no guarantees that this will happen, particularly if the Prime Minister is determined to continue with an exhausted administration.
– What else is there?
He then goes back to the Conservative MPs if they want to make a new effort to oust him.
Traditionally, it would be up to Sir Graham Brady, the chairman of the backbench 1922 Committee, to go to the Prime Minister and tell him that he has lost the support of his MPs and should go.
If that fails, elections will be held on Monday for the 1922 executive, which is responsible for setting the rules of leadership.
Johnson is currently safe from another vote of confidence for 12 months after surviving a challenge last month.
However, if he is still in office, the new executive is likely to consider a rule change that could allow a second vote of confidence, possibly before MPs take a summer recess later this month.
– If I lost that vote, would Mr. Johnson have to go?
That would mean he was out as party leader, but not necessarily as prime minister.
Reports have suggested he might refuse to give up a prime minister but would instead seek to call an early general election, citing his mandate of 14 million voters in the last general election.
That would clearly be a nuclear option, which would pose a host of practical problems.
Some senior Tories believe senior civil servants would try to dissuade him, warning that it would be “inappropriate” to put the Queen in a “difficult position” by calling for dissolution in such circumstances. But would you listen?
– So what is the end game?
Under the UK’s unwritten constitution, any prime minister derives his authority from his ability to conduct the business of his government through Parliament.
If the Government loses an important piece of legislation, particularly a money bill, then the Prime Minister is expected to leave.
Alternatively, Conservative MPs could combine with the opposition to defeat him in a House of Commons vote of confidence, something they would normally be deeply reluctant to do.
And if all else fails, the country will truly be entering uncharted waters.