How Boris Johnson Was Forced Out, and What Happens Next

LONDON — One of his predecessors described him as a “greased piglet”: a man who could slip out of any tight situation.

And despite a damaging scandal involving parties during Britain’s coronavirus lockdown that brought him a fine and a stinging official report, Prime Minister Boris Johnson might have expected to be in a strong position.

A little less than three years ago, Mr. Johnson led the Conservative Party to its biggest election victory in decades. Until the next general election — on a date set by the prime minister, and potentially as late as January 2025 — only his own party’s lawmakers could force him out.

Here’s a guide to how he got to that point, and to the process that will decide his replacement.

The trouble started with ‘partygate,’ but it didn’t end there.

Since late last year, Mr. Johnson has been grappling with a series of reports about parties in Downing Street, where British prime ministers both live and work, while Covid lockdown rules were in force. The scandal became known as “partygate.”

In May, a long-awaited internal inquiry by a senior civil servant, Sue Gray, found that 83 people violated the rules at parties, during which some drank heavily, fought with each other and damaged property. The London police said they had imposed 126 fines for breaches of social distancing. Mr. Johnson himself received only one, for a surprise lunchtime birthday celebration, despite being present at several gatherings for which others were fined.

But in a country that banned almost all social contact for months and kept lesser, but still onerous, restrictions far longer, the claims of rule-breaking have packed an extraordinary emotional punch. Members of Parliament responded to Mr. Johnson’s initial denials of wrongdoing, and then to his apologies, with testimony from people who were barred from visiting dying relatives at the time of the gatherings.

A series of sexual misconduct scandals among Conservative lawmakers further damaged Mr. Johnson. This week’s resignations came after the departure of Chris Pincher, a deputy chief whip — responsible for keeping Conservative lawmakers in line — who was placed in that job by Mr. Johnson despite accusations of inappropriate behavior. Ministers and other officials denied on Mr. Johnson’s behalf that he had been aware of those accusations, only for successive accounts to rapidly unravel.

Boris Johnson’s critics had already tried and failed to remove him.

In Britain, it is hard to get rid of a prime minister, but far from impossible. The job goes to the leader of the political party with a parliamentary majority. The party can oust its leader and choose another one, changing prime ministers without a general election.

Under the Conservative Party’s rules, its members of Parliament can hold a binding vote of no confidence in Mr. Johnson if 15 percent of them — which currently means 54 lawmakers — write to formally request one. That moment came for Mr. Johnson on June 6, with a vote the same evening.

Mr. Johnson received 211 votes — just under 60 percent of his party’s 359 lawmakers — with 148 against him.

That’s a weaker result than it sounds, because almost half of those lawmakers also had government jobs that normally oblige them to back Mr. Johnson. That vote was a secret ballot, however, so it is impossible to know if all of them did.

But then came the cabinet resignations.

For a prime minister in trouble, winning a no-confidence vote is essential, but not always enough. Margaret Thatcher and Theresa May were both out of office within a year of defeating a leadership challenge, by larger margins than Mr. Johnson.

One key factor is whether cabinet ministers rebel. The catalyst for Mrs. Thatcher’s demise in 1990 was the resignation of Geoffrey Howe, a disaffected former ally, and Mrs. May lost several ministers, including Mr. Johnson, who quit as foreign secretary in 2018.

On Tuesday evening, two of Mr. Johnson’s top ministers — Rishi Sunak, the chancellor of the Exchequer, and Sajid Javid, the health secretary — resigned within minutes of one another. More decisively, a flood of further resignations followed, with more than 50 members of Parliament quitting cabinet roles or other government positions by Thursday morning, including some appointed to replace those who had already resigned.

And there was heavy pressure behind the scenes.

The next stage was once known as a visit from the “men in gray suits,” a phrase dating from an age when all key power brokers were men. In those days, when a group known as the “magic circle” chose the Conservative leader, such bigwigs could withdraw support, too. And leaders can sometimes still be persuaded to depart on their own terms rather than be booted out.

Mrs. May resigned in 2019, after surviving a leadership vote, when it was clear that her position had become hopeless. Similar pressure, accompanied by ministerial resignations, was used to evict Tony Blair, the Labour Party prime minister, from Downing Street in 2007. On Wednesday, Downing Street was practically a catwalk for gray suits, with a parade of ministers and party officials visiting Mr. Johnson and seeking to convince him that his position was untenable.

Mr. Johnson was not easily convinced. On Wednesday night, he even fired his housing secretary, Michael Gove, a fellow Brexit campaigner and Conservative power broker who was reportedly among the first to make a private appeal to him that day.

On Thursday morning, Mr. Johnson let it be known that he had changed his mind, acknowledging in a speech later that day that it was clearly “the will of the parliamentary Conservative Party” that he step aside.

There isn’t a clear successor.

One of the reasons that Mr. Johnson’s ousting was so messy is because there is no consensus on who would replace him.

Mr. Sunak, once considered the most likely successor, has himself suffered a fall from grace. He was fined for attending the same party as Mr. Johnson, and has also faced damaging reports around the tax status of his wealthy wife.

Liz Truss, the foreign secretary, has remained in the government and is a leading contender. So, from outside the government, is Jeremy Hunt, the former health secretary who lost to Mr. Johnson in the last Conservative leadership contest. Several others may run, including Mr. Javid, who gave a finely calculated resignation speech. Polling of party members suggests that Ben Wallace, the defense secretary, or Penny Mordaunt, a trade minister, could be strong candidates if they run.

But they all need to be careful. In the past, ambitious rivals have suffered from being seen as disloyal (though not Mr. Johnson, who opposed Mrs. May and then succeeded her).

And it might take a while to chose one.

Mr. Johnson’s plan to remain in 10 Downing Street until a successor is chosen follows the pattern of his two most recent predecessors.

But the timetable for the leadership contest is not in his hands, and it does not follow a published set of rules.

The details and the schedule will be set by the same committee of backbench Conservative lawmakers that makes decisions about no-confidence votes. It is called the 1922 Committee, in honor of the meeting that decided another episode of party tumult a century ago.

What is known is that there will be a two-stage process, whose details are set out in a briefing from the British Parliament’s library.

First, Conservative lawmakers hold a series of ballots among themselves to whittle the number of contenders down to two. In 2019, when Mr. Johnson won, the process began with 10 candidates, and took six ballots. This time, lawmakers reportedly hope to be done before Parliament takes its summer vacation, which starts on July 21.

Then, the party’s entire dues-paying membership gets a ballot to chose between the final two. As of last year, according to a speech by a party official, there were about 200,000 Conservative Party members; they pay a standard annual subscription of 25 pounds, about $30.

The last two candidates in 2019, Mr. Johnson and Mr. Hunt, were given six weeks to make their cases. The result of the membership vote was announced some 46 days after Mrs. May had resigned as party leader, and Mr. Johnson visited Queen Elizabeth to be appointed prime minister the next day.

In this case, the contest will most likely be completed in early September. That would give the new prime minister time to prepare for a major televised speech at the Conservative Party’s annual conference the next month.