A new prime minister will be chosen next week after Liz Truss announced her resignation.
After insisting less than 24 hours earlier she is a “fighter, not a quitter”, the Conservative party leader stood at a podium outside 10 Downing Street on Thursday to say her brief time in the top job will come to an end.
There are now growing calls for an early general election.
Deputy Liberal Democrat leader Daisy Cooper said Boris Johnson should be barred from competing in the Tory leadership contest.
“The fact that Conservative MPs are even considering putting Boris Johnson back in Number 10 shows how out of touch they really are,” she said.
“Boris Johnson was forced to resign in disgrace after countless lies, scandals and failures. He shattered public trust in the government and plunged the UK into a political crisis. He must never be allowed near Downing Street again.
“The future of our country should be in the hands of voters, not the Conservative MPs who have caused all this chaos.”
Justin Tomlinson said it was “wishful thinking” to imagine that Boris Johnson could return as prime minister.
The Tory MP, who described himself as someone who had strongly supported the former prime minister in the past, told Sky News: “I just think it’s too soon. I was there supporting him to the very end but he did lose the confidence of the majority of our colleagues.
“I don’t think a sufficient enough time has probably passed for the party to then unite behind him and for me this now is about us, frankly, being grown up, being pragmatic and putting the country first.”
No. 10 has released a video of Ms Truss’s statement in full.
She said: “I came into office at a time of great economic and international instability.
“Families and businesses were worried about how to pay their bills.
“Putin’s illegal war in Ukraine threatens the security of our whole continent.
“And our country had been held back for too long by low economic growth.
“We delivered on energy bills and on cutting national insurance.
“And we set out a vision for a low tax, high growth economy – that would take advantage of the freedoms of Brexit.
“I recognise though, given the situation, I cannot deliver the mandate on which I was elected by the Conservative Party.
“I have therefore spoken to His Majesty The King to notify him that I am resigning as Leader of the Conservative Party.
“This morning I met the Chair of the 1922 Committee Sir Graham Brady.
“This will ensure we remain on a path to deliver our fiscal plans and maintain our country’s economic stability and national security.
“I will remain as Prime Minister until a successor has been chosen.
US president Joe Biden said in a statement: “The United States and the United Kingdom are strong Allies and enduring friends — and that fact will never change.
“I thank Prime Minister Liz Truss for her partnership on a range of issues including holding Russia accountable for its war against Ukraine.
MP Bob Seely, who backed Penny Mordaunt in the summer’s Conservative Party leadership contest, said he hoped she would run for leader.
Mr Seely also said he predicted “quite a high threshold” for MPs to stand for leader, while also indicating that he did not want to “go back” to the time when Boris Johnson was leader.
“Good luck to Boris. I don’t want to go back to a few months ago where we were so whoever is going to get through I think there’s going to be quite a high threshold,” he told Sky News.
Backing Ms Mordaunt, Mr Seely said: “I think she has a great set of qualities. She has lots of ministerial experience. I think she comes across very well. And I think she resonates with people.
“Right now when we are facing a couple of international crises, both in energy, but also in the Ukraine war, having somebody with stature, with government experience, who can resonate with people, I think is really important.”
Another former Labour leader, this time Ed Miliband, has called for a general election, joining Jeremy Corbyn and current leader Sir Keir Starmer.
He wrote on Twitter: “The Conservative Party is unfit to govern. 12 years of failure, 5 Prime Ministers, and working people paying the price. We need a General Election now.”
Government minister Sir James Duddridge said it was time for a comeback by Boris Johnson.
Tweeting with the hashtag #bringbackboris, he said: “I hope you enjoyed your holiday boss. Time to come back. Few issues at the office that need addressing.”
Sir James had served as a parliamentary private secretary to Mr Johnson when he was in No 10.
Penny Mordaunt has insisted she will “keep calm and carry on” as she was teased about her leadership ambitions following Liz Truss’s resignation.
Former Irish premier Bertie Ahern has criticised Liz Truss, who has resigned as the UK’s Prime Minister, describing her stance on the Northern Ireland Protocol negotiations as unhelpful.
Mr Ahern said he hopes whoever becomes the next prime minister will take a “proactive” approach to the talks with the EU.
The former Fianna Fail leader, one of the architects of the Good Friday Agreement, told an Irish parliamentary committee that the Prime Minister had changed on his way through the door of the committee.
“Whoever the British Prime Minister is, hopefully they will take a bit of a proactive position,” Mr Ahern said.
“What she said yesterday was that even if there was negotiations, that what was in the legislation would be the bottom line.
“Now, I never tried negotiations that declared the bottom line before I went into the negotiation, so that’s clearly not going to solve anything.”
Sinn Fein vice president Michelle O’Neill called on political parties in Northern Ireland to unite to “stand up to the Tories”, following the resignation of Liz Truss.
She tweeted: “The chaos & disastrous policies of the Tories has heaped misery onto workers & families.
“Liz Truss joins the long line of British Prime Ministers who have failed people
“We need all parties in the North to work together, stand up to the Tories & support people in a new Executive.”
Liz Truss will still have to meet the King in person to formally tender her resignation, as is tradition.
This will take place immediately before the monarch asks her successor, also in person, to form a government.
Charles as sovereign plays an important constitutional role in the appointment of a new prime minister.
The Royal Encyclopedia states that the appointment of a prime minister is “one of the few remaining personal prerogatives of the sovereign”.
It says that, in the normal course of events, the monarch does not act on advice nor need to consult anyone before calling upon the leader with an overall majority of seats in the House of Commons to form a government.
But the monarch is guided by constitutional conventions and can seek advice from the outgoing prime minister, any other political leader, senior privy counsellors, or whomever they please within the limits of prudence and caution.
The King spoke to Liz Truss on the phone, when she informed him she was resigning, the same day as holding the first credentials presentations of his reign at Buckingham Palace.
Charles welcomed the Ukrainian ambassador Vadym Prystaiko and the High Commissioner for Pakistan Moazzam Ahmad Khan on Thursday.
He also later held an audience with the president of the Togolese Republic, Faure Gnassingbe.
Liberal Democrat leader Sir Ed Davey told the PA news agency: “Liz Truss trashed our economy and before her Boris Johnson failed our country.
“The Conservatives have shown time and time again that they are not fit to govern our great country.
“We don’t need another Conservative prime minister lurching from crisis to crisis, letting the British people down, increasing their mortgages, not tackling the economic problems.
“The only way we are going to sort this out is if the Conservative MPs for once do their patriotic duty and work with the opposition to get the general election our country needs to let the British people have their say.”
Sir Keir Starmer said: “The risk at the moment is continuing with this chaos, not having a stable Labour government.
“So that’s why there needs to be a general election.
“We can’t just allow the Tory party to keep putting up the next candidate in the middle of this chaos.
“There is a choice, there’s a Labour Party that’s capable of stabilising the economy, has a clear plan and the public are entitled to choose between that stable Labour government and this utter chaos.
“We are ready to form a government, to stabilise the economy and implement a real plan for growth, for living standards, to help people through a cost-of-living crisis.
“And that’s the choice now, a stable Labour government or this utter chaos from the Conservatives.”
Shadow Northern Ireland secretary Peter Kyle said the Prime Minister’s resignation spells more “uncertainty” for Northern Ireland.
The Government has been insisting that another Assembly election will be called in a matter of days, if powersharing is not restored.
Mr Kyle tweeted: “Northern Ireland has suffered enough from Tory neglect.
“At this critical time, with assembly elections looming and crucial negotiations ongoing, the Tories plunge Northern Ireland into yet more uncertainty.”
He said his party “stands ready to be the honest broker Northern Ireland needs”.
Professor Richard Toye, from the University of Exeter, said: “Liz Truss had a difficult hand and played it appallingly, resulting in her becoming the shortest serving British prime minister in history.
“Her tenure deserves to be remembered as more than the answer to a Trivial Pursuit question, however, because it symbolised the logical outcome of a broader crisis that for years has gripped the Conservative Party and the UK political system more generally.
“Liz Truss may not be remembered as the person who definitively killed the Tories as a political force.
“That honour will perhaps fall to her successor.”
Mark Drakeford, the First Minister of Wales, said: “This has been a complete and utter failure of government, with everyone in this country now having to pay the price.
“The complete lack of leadership is preventing decisions and actions from being taken to deal with the many challenges we are facing and help people over what is going to be a very difficult winter.
“A general election is now the only way to end this paralysis.”
Liberal Democrat peer Lord Paddick accused the Government of treating the public with “contempt”.
He said: “Now two prime ministers have resigned, how can this Government continue to treat the electorate with contempt by refusing to call a general election?
“When will Conservative MPs do their patriotic duty and put country before party and trigger a general election?”
Sir Graham Brady, chairman of the Tory 1922 Committee, was vague about whether one or two candidates would be likely to run for the Conservative Party leadership.
He told reporters: “The party rules say there will be two candidates unless there is only one candidate.”
Pressed on whose idea it was to truncate the process into one week, he said: “I think it’s a matter on which there is a pretty broad consensus”.
Sir Graham also said: “It certainly is not the circumstances I would wish to see.”
Conservative former leader Sir Iain Duncan Smith told the PA news agency “it’s time to get real” when asked about Liz Truss’s resignation.
Former Cabinet minister Michael Gove will not stand for the Tory leadership, allies said.
Labour leader Sir Keir Starmer said: “What a mess, this is not just a soap opera at the top of the Tory party, it’s doing huge damage to our economy and to the reputation of our country.
“The public are paying with higher prices, with higher mortgages, so we can’t have a revolving door of chaos.
“There is an alternative and that’s a stable Labour government and the public are entitled to have their say and that’s why there should be a general election.”
Leader of the Opposition in the House of Lords, Lady Smith of Basildon, weighed in on the “utter shambles” of the Government chaos, calling for a general election.
She told the upper house: “Crisis after crisis just heaped on this Government, yet who is paying the price for that?
“It’s the people of this country, who are seeing their prices on food go up, they’re seeing increased bills on fuel, they don’t know what’s happened to their mortgage payments.
“And the Government thinks the answer to all this is to shuffle the deckchairs on the Titanic.
She said the Government now has “no mandate to govern” and that the next prime minister needs the consent of the British people through a general election.
1922 Committee chairman Sir Graham Brady has said he expects Tory members to be involved in choosing a new party leader.
Asked if the party faithful will be included in the process, he told reporters: “Well, that is the expectation.
Sir Graham added: “I think we’re deeply conscious of the imperative in the national interest of resolving this clearly and quickly.”
Former Labour leader Jeremy Corbyn said in a tweet: “The debacle of Liz Truss’ short-lived premiership is a symptom of a broken economic system and a trashed democracy.
“We will continue to lurch from crisis to crisis — and ordinary people will pay the price — until we finally build a society for the many, not the few.”
Sir Graham told reporters: “I have spoken to the party chairman Jake Berry and he has confirmed that it will be possible to conduct a ballot and conclude a leadership election by Friday the 28th of October.
“So we should have a new leader in place before the fiscal statement which will take place on the 31st.”
The new prime minister will be in place before the fiscal statement on October 31, Sir Graham Brady, the chairman of the 1922 Committee of backbench Tory MPs, said.
Ireland’s finance minister Paschal Donohoe has said he is looking forward to continuing Ireland’s close friendship with the UK in the wake of Liz Truss’s resignation as Prime Minister.
He said: “The political and the economic stability of the United Kingdom is a vital ingredient in the economic prospects of Ireland and indeed of Europe, and the Government of the United Kingdom has reaffirmed their commitment to budgetary and economic standards.
“We always affirmed the value of that close friendship and we really look forward in the time ahead to continuing that close friendship and co-operation with the new prime minister of the United Kingdom.”
Former MEP David Bannerman said it is “Boris or oblivion”. In a tweet, he wrote: “I backed @trussliz against Rishi & am v sorry for her. She tried to do right things & unleashed same kind of coup Boris faced. But to me only sensible course of action now is to Bring Back Boris. I will be fully supporting his return. MPs must understand: it’s Boris or oblivion.”
Lawyer, vlogger and campaigner Peter Stefanovic said on Twitter: “This is not just about the Conservative party losing confidence in the Prime Minister. It’s about the whole country having lost all confidence in the conservative party. Truss had no mandate from the country & neither will next PM (the 3rd in four months!). Democracy demands a GE”
The UK’s top business group, which represents 190,000 firms, says the next prime minister must restore confidence and stability following Ms Truss’s resignation after 44 days in office.
Tony Danker, director-general of the CBI, said: “The politics of recent weeks have undermined the confidence of people, businesses, markets and global investors in Britain. That must now come to an end if we are to avoid yet more harm to households and firms.
“They will need to deliver a credible fiscal plan for the medium term as soon as possible, and a plan for the long-term growth of our economy.”
Yields on gilts – UK government bonds – have eased slightly in response to Ms Liz Truss’s decision to resign.
UK 30-year gilt yields, which fall as price improve, fell back by 0.44% to 3.86% on Thursday.
Yields had dropped even further shortly before the Prime Minister’s statement at 1.30pm but sprang back slightly.