Boris Johnson has become the new Conservative leader on Tuesday in London, winning the race to be Britain's prime minister.
After exhausting all possible avenues to get her Brexit plan through parliament, Theresa May stepped down as party leader on June 7, triggering a six-week leadership contest.
WATCH: Tearful Theresa May announces resignation
Some 160 000 grassroots Conservative party members had the chance to choose their new leader.
Johnson, who has vowed to take Britain out of the European Union on the October 31 deadline, with or without a deal, is set to march head-on into a collision with Brussels, the British parliament and Tehran.
The former London mayor, who charms and alarms colleagues in equal numbers, beat Foreign Secretary Jeremy Hunt and will take over from Theresa May as prime minister on Wednesday.
But the incoming premier faces exactly the same set of circumstances - if not worse - with parliament deadlocked as the Brexit deadline looms.
The new leader will have just three months to attempt to resolve a three-year Brexit crisis that could damage economies on both sides of the Channel and determine the fate of generations of Britons.
READ: Who blinks first? Boris Johnson's risky Brexit bet
Resignations
Johnson's seemingly imminent appointment triggered some ministers to announce their resignations, including finance minister Philip Hammond.
Alan Duncan quit as Britain's Europe and Americas minister on Monday - and tried to bring down Johnson's leadership before he even takes office.
"I have very grave concerns that he flies by the seat of his pants and it's all a bit haphazard and ramshackle," Duncan told the BBC.
"I just think he's going to go smack into a crisis of government."
He tried to force a test of Johnson's support in parliament via an emergency debate on Tuesday, which was rejected by Commons Speaker John Bercow.
Politics in Britain has become increasingly polarised around the Brexit issue, with both the Conservatives and the infighting-riven Labour main opposition haemorrhaging support.
The Liberal Democrats, the biggest unambiguously anti-Brexit opposition party, on Monday announced Jo Swinson as their new chief after their own leadership contest.
"I will do whatever it takes to stop Brexit," the 39-year-old Scot said.
The Britain Elects opinion poll aggregator puts Labour on 25%, the Conservatives on 23, the Brexit Party on 21 and the Lib Dems on 18, highlighting the four-way split.
Stand-off with Iran
Besides his domestic battles, Johnson will have to try to secure a resolution to the stand-off with Iran.
READ MORE: The 5 big problems Britain's next prime minister will have to deal with on his first day
In a dramatic escalation of tensions, Tehran seized the British-flagged Stena Impero on Friday in the strategic Strait of Hormuz, against a backdrop of brinkmanship between the United States and Iran.
Speaking in parliament on Monday, Hunt branded Tehran's actions as "state piracy".
He announced that Britain was planning a European-led protection force for shipping in the Gulf.
May will answer questions in parliament as prime minister for the final time at midday (11:00 GMT) on Wednesday.
She will then make one last speech outside the premier's Downing Street office before heading to Buckingham Palace to tender her resignation to Queen Elizabeth II.
The 93-year-old head of state will then invite the new Conservative leader to form an administration.
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