Boris Johnson's allies warned there is a "deep pit in Hell" waiting for Michael Gove after the Justice Secretary stabbed his fellow Brexit champion in the back saying he was not up to being Prime Minister.
Mr Gove delivered a brutal verdict on Mr Johnson's capabilities and questioned whether his "heart and soul" were in taking us out of the EU, effectively ending his hopes of succeeding David Cameron, as he announced his own bid for Downing Street.
Damning his friend with faint praise, Mr Gove said he had "enjoyed working with him" during the referendum campaign. But he said: "I realised in the last few days that Boris isn't capable of building that team and providing that unity.
"And so I came reluctantly but firmly to the conclusion that as someone who had argued from the beginning that we should leave the European Union and as someone who wanted ensure that a bold, positive vision for our future was implemented, that I had to stand for leadership of the Conservative party."
He added: "I thought it was right that following the decision that the people took last week that we should have someone leading the Conservative party and leading the country who believed in their heart and soul that Britain was better off outside the European Union."
As the blows rained down on Mr Johnson this morning, key backers Nick Boles and Dominic Raab defected to Mr Gove's campaign and arch-rival Theresa May won support from Leader of the House Chris Grayling - another Brexit champion.
Within hours Mr Johnson, who had been the hot favourite, was using an event that had been intended as his campaign launch to rule himself out.
Tory MP Jake Berry posted on Twitter: "There is a very deep pit reserved in Hell for such as he. #Gove"
And an aide is said to have texted a journalist: "Gove is a c*** who set this up from the start."
Mr Johnson's father Stanley cited the famous Shakespeare rebuke from Julius Caesar after his friend Brutus stabbed him. "'Et tu Brute' is my comment on that," he told BBC Radio 4. "I don't think he is called Brutus, but you never know."
In his speech, Mr Johnson said the next Prime Minister had to seize Britain's "moment to stand tall in the world.
"But I must tell you, my friends, you who have waited faithfully for the punch line for this speech, that having consulted colleagues and in view of the circumstances in Parliament, I have concluded that person cannot be me," he said.
"My role will be to give every possible support to the next Conservative administration, to make sure that we properly fulfill the mandate of the people that was delivered at the referendum and to champion the agenda I believe in."
The Conservatives' ruling 1922 committee has confirmed that the candidates are Mrs May, Mr Gove, Treasury minister Andrea Leadsom, Work and Pensions Secretary Stephen Crabb and ex-defence secretary Liam Fox.
Mr Johnson saved his shock withdrawal for the end of a lengthy valedictory speech in which he stressed his achievements in City Hall and urged the UK to look towards a brighter future outside of the EU.
Mr Gove had been expected to play a key role in Mr Johnson's campaign after the pair worked hand in glove to deliver victory for Brexit in the historic referendum. He has repeatedly ruled out making a bid for Downing Street in the past - including memorably offering to record his denial in blood on a parchment.
However, there were hints of tensions with Mr Johnson last night when an email written by Mr Gove's wife surfaced which urged him to seek assurances on key issues.
Brexit supporters had been alarmed by an article Mr Johnson penned earlier this week in which he suggested that access to the single market could be more important than curbing immigration.
The ex-mayor's team have been engaged in a desperate effort to reassure Leave-supporting MPs that he will not "backslide" after the referendum. Anxieties were heightened by the fact he was thought to have switched sides to campaign for Brexit at the last minute.
David Cameron's biographer Anthony Seldon claimed in an article today that Mr Johnson's decision "went down to the wire" and Downing Street aides believed he was primarily motivated by his desire to become Prime Minister.
The email from Mr Gove's wife, which surfaced last night after apparently being sent to the wrong person in error, urged him to seek "reassurance" from "Boris" about his role in future plans before pledging his support.
Sarah Vine, who is a Daily Mail columnist, said that without these assurances, her husband should not be prepared to side with the former London Mayor in his battle for Number Ten.
Mr Johnson was given just five minutes' warning before Mr Gove released his statement saying he was the best man to make Britain "stronger and fairer". He said the post-Brexit period was a "unique chance to heal divisions, give everyone a stake in the future and set an example as the most creative, innovative and progressive country in the world".
Mr Gove acknowledged he had repeatedly said he did not want to be PM and but admitted events since the referendum had "weighed heavily with me".
"The British people voted for change last Thursday. They sent us a clear instruction they want Britain to leave the EU and end the supremacy of EU law," he said in a statement.
"They told us to restore democratic control of immigration policy and to spend their money on national priorities such as health, education and science instead of giving it to Brussels.
"They rejected politics as usual. They want and need a new approach to running this country.
He added: I have come reluctantly to the conclusions Boris cannot provide the leadership or build the team for the task ahead.
"I have therefore decided to put my name forward for the leadership."
The shift triggered a massive swing of support away from Mr Johnson, whose team had previously been boasting of having up to 100 MPs on board.
Justifying his decision in an interview later, Mr Gove insisted a Brexit supporter should now run the country.
"And I hoped that Boris Johnson would be someone who could ensure that the Government follow the instructions of the British people and also build and unite a team around him in order to lead this country forward," he said.
Among the other fast-moving developments on another breathless day in politics:
• Theresa May confirmed she was standing for leader and said she would abandon the government's target for eradicating the deficit in the wake of the Brexit vote.
• The Home Secretary swiped at Eton-educated Mr Johnson for having no clue about the experience of everyday people.
• She also dismissed his ability to negotiate a new deal with the EU, mocking him for having bought 'three nearly new water cannon' last time he negotiated with the Germans.
• Tory heavyweights started picking sides in the leadership battle, with Health Secretary Jeremy Hunt dropping his own ambitions and supporting Mrs May. Education Secretary Nicky Morgan, who had also been mulling a run, said she would back Mr Gove.
• Labour leader Jeremy Corbyn lashed out at Mr Johnson and Mr Gove for 'hateful racism' during the EU referendum campaign.
Theresa May launched a stinging assault on Mr Johnson today as she formally announced she is a candidate amid polls giving her a clear lead in the race.
At a press conference held within minutes of Mr Gove's bombshell, she insisted the country needed someone with "experience" at a time of huge change, jibed that he did not understand the lives of ordinary people, and pointed out that the last time he negotiated with the Germans he bought "three nearly new water canons".
Mrs May also dramatically announced that she will abandoned the government's whole austerity plan if she ends up in Number 10.
She said there would no longer be a target to eradicate the deficit by 2020.
Despite campaigning for Remain, the Home Secretary promised to take Britain out of the EU and curb the free movement of migrants.
Mrs May said she would appoint a Cabinet Minister for Brexit who will be a Eurosceptic.
She also argued that Article 50 - the formal mechanism for starting our exit from the EU - should not be triggered until the end of the year,
"We need leadership that can unite our party and our country. With the Labour Party tearing itself apart and divisive nationalists in Scotland and Wales , we need a government working in the best interests of the whole country," she said.
"We need a bold, new positive vision for the future of our country."
She also ruled out a snap general election: "There should be no general election until 2020, there should be a normal Autumn Statement and no emergency Budget and there should be no decision to invoke Article 50 until the British negotiating strategy is agreed and clear, which means Article 50 will not be invoked until the end of this year."
Mrs May said the UK should abandon austerity measures and efforts to tackle the deficit.
"While it is absolutely vital that the Government continues with its intention to reduce public spending and cut the budget deficit, we should no longer seek to reduce a budget surplus by the end of the Parliament," she said.
If before 2020 there is a choice between further spending cuts, more borrowing and tax rises, the priority must be to avoid tax increases since they would disrupt consumption, employment and investment.'
Asked whether she was the best person to negotiate with European leaders, she took the chance to take a swipe at Mr Johnson's negotiation skills.
"As to why I am the best person who can negotiate with Angela Merkel, well I would simply say this: I have done this, I have sat round the table, I know what it's like in those European meetings.
"I've not just done it, I've delivered on negotiations. Now of course, I know other people have also negotiated in Europe, I mean I think Boris negotiated in Europe - I seem to remember last time he did a deal with the Germans he came back with three nearly new water canons," she joked, joining the room in laughter.
In another slap at Mr Johnson, she said unlike others she was not motivated by "ambition or glory".
"I know some politicians seek high office because they're driven by ideological fervour. I know other seek it for reasons of ambition or glory. But my reasons are much simpler," Mrs May said.
"I grew up the daughter of a local vicar and the granddaughter of a regimental sergeant major.
"Public service has been a part of who I am for as long as I can remember.
"I know I'm not a showy politician; I don't tour the television studios, I don't gossip about people over lunch, I don't go drinking in parliament's bars, I don't often wear my heart on my sleeve, I just get on with the job in front of me."
Mrs May said: "A vision of a country that works not for a privileged few but for everyone of us.'
Mrs May said there could be no going back on Brexit - but said she did not believe Article 50 should be invoked before end of the year.
And she ruled out a general election before 2020 if she wins the election.
Mrs May said "strong proven leadership" was needed to hammer out a good deal with the EU and she announced a new department would be set up to handle Brexit - led by a Secretary of State who campaigned for Leave.
She said: "Nobody should fool themselves that this process will be brief or straightforward.
"It's going to take a period of several years to disentangle from the rules and processes of Brussels."
She added: "I want to be clear that as we conduct our negotiation, it must be a priority to allow British companies to trade in goods and services within the single market but also regain more control over the number of people coming here from Europe."
Last night there was a boost to Mrs May's leadership ambitions after Tory members gave her a 17-point lead over Mr Johnson.
In the first poll of party members since the EU Referendum, support for Mrs May was at 55 per cent and at 38 per cent for Mr Johnson.
Tory members had been asked which of the pair they would support if they were head-to-head in the final round of the contest.
The poll was carried out by YouGov for The Times.
She will say that her vision as PM will be to restore battered public trust in politics by presiding over a Government that "works not for a privileged few but for every one of us".
Two hours after her official declaration, Mr Johnson will officially unveil his own "Back Boris in 2016" campaign.
The ex-London mayor will pledge "opportunity" for all and urge Britain to believe in itself again post-Brexit.
Yesterday, Mrs May's aides vowed there would be "no deals" cut with Mr Johnson - triggering a potentially bruising nine-week battle for the top job that both have coveted for years.
Writing in The Times, Mrs May set her sights on Mr Johnson's privileged background as she attacked unnamed Westminster figures who do not appreciate hardship and believe the government 'is a game'.
Appealing to blue-collar Tories she wrote: "If you're from an ordinary, working-class family, life is just much harder than many people in politics realise.
"You have a job, but you don't always have job security. You have your own home, but you worry about mortgage rates going up.
"Frankly, not everybody in Westminster understands what it's like to live like this.
"And some need to be told that what the government does isn't a game, it's a serious business that has real consequences for people's lives."
Westminster has been rife with intrigue and backroom deals as the leading contenders lobbied for support.
Mrs May has secured backing from Foreign Secretary Philip Hammond, International Development Secretary Justine Greening and housing minister Brandon Lewis, who praised her sincerity and serious style.
Other supporters unveiled by Mrs May yesterday include justice minister Mike Penning - a former top aide to Iain Duncan Smith who campaigned for Leave.
Allies point to her achievements as the longest-serving home secretary in more than half a century, including introducing modern slavery bill and limiting the use of stop and search, which was being disproportionately targeted at young black men.
But until this morning Mr Johnson was thought to be well ahead to have 100 supporters while Mrs May reportedly had between 50 and 80.
Yesterday it emerged that an attempt to bring the two together on a joint ticket failed when Mr Johnson was kept waiting for 20 minutes by the Home Secretary, who announced she was not coming.
Mrs May's spokesman declared after the incident was revealed: "Theresa is in it to win it. She does not want any deals. She would rather lose than do a deal."
SNP leader Alex Salmond labelled Mr Gove as "Lord Macbeth" for having 'dispatched' Prime Minister David Cameron before knocking Boris Johnson out of the Tory leadership race.
The former SNP leader also asked Commons Leader Chris Grayling, who is backing Home Secretary Theresa May's leadership bid, if he feared he will soon be targeted by Mr Gove.
To laughs, Mr Salmond suggested to Mr Grayling: "Can we have a week-long debate on political backstabbing?
"We're going to need a week because all of the PLP (Parliamentary Labour Party) will want to take part, but they are rank amateurs compared to (Mr Gove), the Lord Macbeth of this chamber, who having dispatched the Prime Minister today is dispatching the Prime Minister's greatest rival.
"What makes you think that Lord Macbeth's dagger won't soon be turned to you and the Home Secretary?"
Tory frontbencher Mr Grayling replied: "(Mr Gove) has been, in my view, an excellent education secretary, an excellent chief whip and is now doing an excellent job in the role I used to perform as Lord Chancellor.
"He has friends and the confidence of this side of the House and he is, for the Scottish National Party, a formidable adversary."
Announcing the five candidates today, the chairman of the 1922 Committee, Graham Brady, confirmed the first set of voting will take place on Tuesday as the party's MPs narrow down the field of five candidates to two.
With the least successful contender eliminated at each round, further ballots will be held on Thursday, then successive Tuesdays and Thursdays until two front-runners emerge to be put forward to the party membership in the country for a final decision. Mr Brady said the committee wants a winner to be chosen by September 9.
A handful of Tory MPs reacted with disbelief as news that Mr Johnson would not be seeking the leadership filtered through as they waited for Mr Brady's announcement.
Mr Gove - regarded as an intellectual heavyweight in the cabinet - has seen his once-close friendship with Mr Cameron smashed by the bitter battle over EU membership.
He is now bound to face questions about his repeated denial of leadership ambitions, In 2012 he told Sky News: "I don't want to be prime minister," he told Sky News at the time. "Having seen close up how he does the job, I know that I couldn't do it."
Politicians, he noted, were constantly accused of "leaving the door open' in such denials and suggesting they 'might wriggle out of it at some point".
"I don't know what I can do in a way but if anyone wants me to sign a piece of parchment in my own blood saying I don't want to be prime minister, then I'm perfectly happy to do that."
Pro-EU former deputy Prime Minister Lord Heseltine slammed Mr Johnson for "ripping apart" the Conservative Party and said he would have to "live with the shame of what he has done". Lord Heseltine, the former deputy prime minister, delivered a scathing verdict on Mr Johnson's actions.
"He's ripped the party apart. He's created the greatest constitutional crisis of modern times. He knocked billions off the value of the nation's savings.
"He's like a general who leads his army to the sound of guns and at the sight of the battlefield abandoned the field. I have never seen so contemptible and irresponsible a situation."
He added: "This is a free society; there's no question of punishment. He must live with the shame of what he's done."
The Tory peer dismissed the contribution of other pro-Leave voices such as Mr Gove, saying Mr Johnson was the "one who won the referendum".
"Without him it would not have happened. Without him there would be none of this uncertainty, and he's abandoned the field," he said.
"Quite interesting, actually, one of the allegations upon which the referendum was conducted is that there is an elite group in this country who are out of touch. Well, it's that elite group that now has to pick up the pieces of Britain's self-interest while Boris Johnson abandons any sense of responsibility for what he's done."
Meanwhile, Labour leader Jeremy Corbyn has launched a furious attack on Mr Johnson and Mr Gove for their 'hateful' and 'racist' referendum campaign.
"Boris Johnson ... compared Hitler's murderous tyranny with the European project created from its ashes and questioned Barack Obama's motives because of his 'part-Kenyan heritage," he told a press conference this morning.
"That was no dog whistle. That was a fog horn - a classic racist trope - casting doubt on someone's motivation because of their race.
"The Justice Secretary Michael Gove compared pro-Remain economists to Nazi collaborators, a startling example of the way in which the Nazi regime and the Holocaust can be minimized, trivialized or even forgotten by ill-judged comparisons.
"And Nigel Farage warned of mass sex attacks should the Remain Campaign win, calling it the 'nuclear bomb' of the Brexit campaign. Is it only me who just doesn't find him funny any more?
"These are hateful comments - no question. They are unworthy of the millions who voted to Leave, not out of xenophobia or racism, but often as a desperate response - yes to austerity, but also to years of being ignored and left behind by the Westminster elite."