Former London Mayor Boris Johnson, who had been considered one of the favourites to replace David Cameron as British Prime Minister, has said he won't be standing.
The decision by Johnson, who spearheaded the "Leave" campaign, upended the Conservative Party leadership contest and added to deep uncertainty over how and when the country will split from the European bloc.
Johnson had been tipped as a favourite to succeed Cameron, who resigned after the June 23 referendum saying he would leave it to his successor to begin formal talks with the EU on Britain's departure - despite European leaders insisting on a quick divorce.
During his announcement Johnson listed the qualities required in Britain's new leader, but shocked everyone when he delivered the punchline at the end.
"Let us seize this chance and make this our moment to stand tall in the world. That is the agenda for the next prime minister of this country.
"But I must tell you, my friends ... that having consulted colleagues and in view of the circumstances in parliament, I have concluded that person cannot be me," he told shocked supporters at a press conference in a London hotel.
Johnson made his announcement a couple of hours after fellow Brexit campaigner Michael Gove announced his own surprise bid for the top job, sharply criticising his mop-haired former ally.
In a statement that one MP likened to the actions of the murderous Macbeth in Shakespeare's play, justice minister Gove said Johnson "cannot provide the leadership or build the team for the task ahead".
Johnson appeared to quote some of the words spoken by Brutus before killing Julius Caesar in the Shakespeare play - seen as a reference to the act of political betrayal by Gove.
"Time is not to fight against the tide of history," Johnson said.
Observers were left stunned by the dizzying events in the corridors of power, where opposition Labour leader Jeremy Corbyn is also clinging on to his job after a revolt by MPs.
"It looks a bit like House of Cards and may be too many politicians are watching Game of Thrones at the moment," health minister Jeremy Hunt told SkyNews.
- 'Brexit means Brexit' -
Bookmakers Paddy Power made Theresa May the favourite to be next Conservative leader and therefore prime minister with odds of 8/13, an implied probability of 62 percent.
Gove came second with odds of 11/4 -- a 27-percent chance.
While not seen as a passionate supporter of the EU, May insisted that "Brexit means Brexit" as she launched her campaign.
"The campaign was fought, the vote was held, turnout was high and the public gave their verdict," she added.
May said she would not trigger the formal process for leaving the EU, known as Article 50, until next year, despite pressure from other European countries.
Gove, meanwhile, wants Britain to quit the European single market, saying it should negotiate bilateral trade agreements instead. He suggested during the campaign it could take at least four years to leave the EU.
READ MORE: 'This is going to be far from plain sailing': David Cameron addresses parliament after Brexit
There are a total of five candidates in the race to be Conservative leader, who will automatically become prime minister.
They will be whittled down to two by a series of ballots by Conservative MPs in the coming days before being put to a vote of grassroots party members. The new leader will be announced by September 9.
Cameron said he would resign within hours of last Thursday's 52-48 percent vote to leave the EU, a result that exposed deep rifts in British society and even threatened the unity of the United Kingdom, with Scotland's leader evoking a new independence vote.
- Corbyn digs in -
The Brexit vote sent the pound and stock markets plunging, prompting US President Barack Obama to warn of "longer-term concerns about global growth", a view echoed by the IMF on Thursday.
However, London's FTSE 100 has staged a strong recovery over the last 48 hours, closing higher on Wednesday than its level before the referendum. World markets continued to climb Thursday.
The outcome, after an often acrimonious campaign, triggered anger among those who wanted to remain in the EU. More than four million people have signed a petition calling for a second referendum.
However, 58 percent of Britons believe the result should stand against 31 percent who think the vote should be re-run, according to a YouGov poll.
The Labour party has also been thrown into turmoil by the vote, as lawmakers moved in its aftermath to oust Corbyn, who has been accused of not campaigning hard enough to stay in the EU.
Though Labour lawmakers this week passed a vote of no confidence against him by 172 to 40, the veteran socialist has refused to resign.
He insists he still has the support of party members and will fight any leadership challenge which he sees as a plot by centrist elements within Labour.