Boris Johnson has resigned as Conservative leader - but he will continue as the United Kingdom's prime minister until a new leader is chosen.
A Conservative leadership race will take place this summer and a new prime minister will be in place in time for the Tory party conference in October.
Johnson publicly announced his resignation outside No 10 Downing Street just after 11.30pm New Zealand time.
He said it was "clearly now the will of the parliamentary party" for there to be a new prime minister.
"I want you to know how sad I am to be giving up the best job in the world," Johnson said.
"But them's the breaks."
Johnson said his arguments to stay in power were rejected due to a "herd instinct" at Westminster.
He said it had been "an immense privilege" to hold the top job but no one in politics was "remotely indispensable".
He was immensely proud of his achievements, including getting Brexit done, getting the UK through the pandemic and leading the West in standing up to Russia's President Vladimir Putin's invasion of Ukraine.
Johnson promised to give the new leader as much support as he could.
He rejected any idea of holding a general election, saying it would be preposterous to change governments when the administration was delivering so much and "when the economic scene is so difficult domestically and internationally".
The process of choosing a new Conservative leader would begin immediately with a timetable to be announced next week.
Before Johnson made his address, Tories were already questioning whether he could stay on as prime minister in the meantime with some suggesting his deputy Dominic Raab take over as a caretaker. Other British political figures also weighed in on the issue, insisting Johnson's tenure was now untenable.
Labour Party leader Sir Keir Starmer demanded Johnson stand down as PM immediately, saying it was not fair on the country for him to stay on as caretaker prime minister.
"He needs to go, he can't cling on," Starmer said.
"His own party has decided it's time - so they can't inflict him on the country for the next few months."
Insisting Labour will take matters into its own hands if necessary, Starmer warned the Tories that if they did not get rid of Johnson "Labour will, in the national interest, bring a no confidence vote - because this can't go on".
"The change we need is not just at the top, we need a change of government. We need a Labour government."
Starmer said the Tory party had inflicted chaos upon the country during the worst cost-of-living crisis in decades. And they cannot now pretend they are the ones to sort it out.
"They have been in power for 12 years. The damage they have done is profound."
Foreign Secretary Liz Truss, who is one of the front runners to replace Johnson, tweeted that Johnson had made the right decision.
"The government under Boris's leadership had many achievements - delivering Brexit, vaccines and backing Ukraine. We need calmness and unity now and to keep governing while a new leader is found," she said.
Conservative MP Robert Buckland said "the views of colleagues" would have pushed Johnson to resign, adding "he has bowed to the inevitable".
He said Johnson managed to "break the logjam on Brexit".
But he said he now hoped the Conservative Party could "get back to values" such as "freedom under the law".
Conservative MP Tobias Ellwood said he was "glad [Johnson] recognised the damage that was being done not just to the party brand but also our international stock".
Ellwood added the party now had a "massive amount of regrouping to do".
Critics, such as Scotland's First Minister Nicola Sturgeon, were also arguing that it will not be be sustainable for Johnson to continue as prime minister for several months, given the huge number of vacancies in government.
Sturgeon said there will be "a widespread sense of relief that the chaos of the last few days [indeed months] will come to an end" as and when Johnson resigns as Conservative leader.
She added that he was always "manifestly unfit to be PM".
Ex-Scottish Conservatives' leader Ruth Davidson said in a tweet: "There's no way he can stay on until October. It's arrant nonsense to think he can."
Dominic Cummings, Johnson's former right-hand man turned nemesis, has urged Conservatives to remove him as prime minister today, rather than let him stay as caretaker prime minister.
Evict TODAY or he'll cause CARNAGE, even now he's playing for time & will try to stay
— Dominic Cummings (@Dominic2306) July 7, 2022
No 'dignity', no 'interim while leadership contest'.
Raab shd be interim PM by evening
George Freeman, who announced he was resigning as science minister today, said Johnson must apologise to the Queen and advise her to call for a caretaker PM immediately.
His comments were backed up by former minister, Nick Gibb who said: "As well as resigning as party leader the PM must resign his office. After losing so many ministers, he has lost the trust and authority required to continue.
"We need an acting PM who is not a candidate for leader to stabilise the government while a new leader is elected."
The deputy chair of the influential 1922 Committee of backbench Tory MPs joined colleagues calling for Johnson to be replaced as prime minister immediately.
Nus Ghani, MP for Wealden, said Raab should take over from Johnson immediately on an interim basis.
Business Minister Kwasi Kwarteng also said the Conservatives needed a new leader as soon as practicable, and insisted the government must continue to operate.
"What a depressing state of affairs. So much needless damage caused," he tweeted.
He said the party needs to choose "someone who can rebuild trust, heal the country, and set out a new, sensible and consistent economic approach to help families".
"The wheels of government must continue in the meantime."
'A figure of absolute disrepute'
The leader of Sinn Fein in Norther Ireland, Michelle O'Neill said: "It has been an utter absurdity that the people here have been subjected to Boris Johnson for any length of time.
"He is a figure of absolute disrepute. Anyone who tries to sabotage our peace agreements, a quarter century of progress and our shared future is truly no friend of ours."
Liberal Democrat Leader Sir Ed Davey said it had long been clear Johnson was "unfit to lead our country", adding the "public won't forgive the Conservatives for propping him up for so long".
The Kremlin has also weighed in on a political leader who has been among the most vocal critics of Russia over its war with Ukraine.
Spokesman Dmitry Peskov said: "He [Johnson] doesn't like us, we don't like him either".
Meanwhile, Britain continues to have a functioning government, Paymaster General Michael Ellis said in a statement to parliament ahead of Johnson's expected resignation.
"We must continue to serve our country ... It is our duty now to make sure the people of this country have a functioning government. This is true now more than ever," Ellis, a minister in the Cabinet Office department which oversees the running of government, said.
How pressure on Johnson snowballed
After a record number of resignations in 24 hours, the pressure on Johnson ramped up even further on Thursday morning, UK time:
- Northern Ireland Secretary Brandon Lewis became the first cabinet minister of the morning to resign, saying things were "past the point of no return"
- He was swiftly followed by a succession of other junior ministers
- No 10 remained silent, with many speculating about what was going on
- Chancellor Nadhim Zahawi, who has only been in post for two days, publicly called for the PM to "go now"
- Immediately afterwards, newly appointed Education Secretary Michelle Donelan resigned, saying she had "pleaded" with the PM to resign
- Less than half an hour later, the news broke that Johnson had agreed to stand down
- BBC / Reuters