Rishi Sunak has apologised after leading the Conservatives to their worst ever election result as a Labour landslide swept Keir Starmer to Downing Street.
The outgoing Prime Minister said he would quit as Tory leader once arrangements are in place to choose his successor, potentially triggering another round of Conservative infighting as MPs scramble to replace him.
Mr Starmer will become prime minister after a Tory rout which saw former prime minister Liz Truss and a dozen serving Cabinet members lose their seats.
After stepping out onto a drizzly Downing Street, Mr Sunak said: "I will shortly be seeing His Majesty the King to offer my resignation as Prime Minister.
"To the country, I would like to say first and foremost, I am sorry.
"I have given this job my all, but you have sent a clear signal that the Government of the United Kingdom must change. And yours is the only judgment that matters.
Watch: Rishi Sunak announces resignation after election defeat
"I have heard your anger, your disappointment, and I take responsibility for this loss."
He apologised to Conservative candidates and campaigners, saying: "I'm sorry that we could not deliver what your efforts deserved.
"It pains me to think how many good colleagues who contributed so much to their communities and our country will now no longer sit in the House of Commons.
"I thank them for their hard work and their service."
He Sunak said he was "proud" of his achievements and believes the UK is "more prosperous, fairer and resilient than it was in 2010".
The outgoing Prime Minister cited the negotiation of the Windsor Framework and efforts to support Ukraine during his premiership.
He also praised Labour leader Keir Starmer as a "decent, public-spirited man who I respect", saying "whatever our disagreements," he wished Mr Starmer and his family well as they make "the huge transition to their new lives behind this door".
Ending his last statement as Prime Minister, he said: "One of the most remarkable things about Britain is just how unremarkable it is that two generations after my grandparents came here with little, I could become Prime Minister. And that I could watch my two young daughters light Diwali candles on the steps in Downing Street.
"We must hold true to that idea of who we are. That vision of kindness, decency and tolerance that has always been the British way.
"This is a difficult day at the end of a number of difficult days. But I leave this job honoured to have been your Prime Minister.
"This is the best country in the world. And it is thanks entirely to you, the British people, the true source of all our achievements, our strengths and our greatness.
"Thank you."
After his speech, Mr Sunak and his wife Akshata Murty, got into a dark blue Audi and were driven away from Downing Street.
Mr Sunak then tendered his resignation during an audience with King Charles.
Earlier, Mr Sunak said it had been a "difficult night" and apologised to Conservative candidates who had lost their seats, as he held onto his own Richmond and Northallerton constituency.
Mr Sunak's apology was echoed by Suella Braverman, but the Tory leadership challenger was sorry for her party's record in government, suggesting it had not listened enough to the electorate.
Elsewhere, former justice Robert Buckland warned that a lurch to the right would be "disastrous" for the party after he lost his Swindon South seat.
Speaking at Northallerton leisure centre after his result came in, Mr Sunak said: "The British people have delivered a sobering verdict tonight, there is much to learn... and I take responsibility for the loss.
"To the many good, hard-working Conservative candidates who lost tonight, despite their tireless efforts, their local records and delivery, and their dedication to their communities. I am sorry."
Mr Sunak held onto his seat with a nearly 13,000 majority over his nearest rival, Labour's Tom Wilson, but conceded defeat for the Tories amid crushing results elsewhere for the party.
Among the Cabinet ministers to lose their seats overnight were Defence Secretary Grant Shapps and Commons Leader Penny Mordaunt to Labour, and Justice Secretary Alex Chalk, Education Secretary Gillian Keegan and Culture Secretary Lucy Frazer to the Liberal Democrats.
Jeremy Hunt won the Godalming and Ash seat in Surrey despite a threat from the Liberal Democrats, and former home secretary Suella Braverman, elected to the new constituency of Fareham and Waterlooville, held onto her seat.
She said "I'm sorry" twice during her victory speech.
"I'm sorry that my party didn't listen to you," she said.
"(The) Conservative Party has let you down. You - the Great British people voted for us over 14 years and we did not keep our promises.
"We've acted as if we're entitled to your vote regardless of what we did, regardless of what we didn't do, despite promising time after time that we would do those things and we need to learn our lesson because if we don't, bad as tonight has been for my party, we'll have many worse nights to come."
Thanking voters in her constituency, Ms Braverman said they were "patriotic, common sense, kindly, dedicated, enterprising".
Asked about it, Mr Buckland told the BBC: "I am afraid that is not an isolated example."
He added: "We can see articles being written before a vote is cast at the General Election about the party heading for defeat and what the prognosis should be.
"It is spectacularly unprofessional, ill-disciplined."
He also warned against a rightward tilt for his party, claiming it "would be a disastrous mistake and it would send us into the abyss, and gift Labour government for many years".
Mr Shapps, who lost his Welwyn Hatfield seat to Labour, said his party had an "inability to iron out (its) differences" amid and endless "soap opera".
And in Portsmouth, outgoing Tory MP Ms Mordaunt said the Tories had lost because they "failed to honour the trust that people had placed in it".
She added: "Our renewal as a party and a country will not be achieved by us talking to an ever smaller slice of ourselves but being guided by the people of our country. And if we want again to be the natural party of government, then our values must be the people's."
