Known for his jokes, gaffes and bluster, Boris Johnson has pitched himself as the big personality Britain needs to steer it through Brexit and thereby save his party from electoral humiliation.
The former foreign minister has dismissed questions about his competence and populist rhetoric with a pitch to take Britain out of the European Union and unite a divided country.
To Conservative colleagues terrified that the political deadlock over Brexit will provoke an early general election, he argues that he is the man to beat the Labour opposition and eurosceptic Nigel Farage's insurgent Brexit Party.
As a leader of the Brexit campaign during the 2016 EU referendum and a two-term mayor of London, Johnson has proved he can reach beyond the Conservative Party's core vote.
But his past quips -- including about gay "bumboys", and Muslim women wearing the face veil looking like "letter boxes" -- have drawn intense criticism.
His promise to leave the EU on the 31 October deadline, with or without a deal, has alarmed the half of voters who rejected Brexit three years ago -- particularly as he offers no detailed plan.
Johnson has also been accused of hiding from scrutiny during the leadership campaign, after he avoided the first televised debate and kept media appearances to a minimum.
- London mayor -
Born in New York in 1964, Alexander Boris de Pfeffel Johnson has always been ambitious -- his sister Rachel said he wanted as a child to be "king of the world".
He first ran for the leadership after the EU referendum, but pulled out when his key ally Michael Gove turned on him to run himself.
This time, he has run a disciplined campaign, which began by trimming his famously unruly mop of blond hair.
He has focused on cultivating backers in parliament, and limiting his public appearances has allowed him to avoid the gaffes that have defined his career.
Educated at the elite Eton school and Oxford University, where he was a member of the rowdy all-male Bullingdon Club, Johnson first worked as a journalist for The Times newspaper.
He was sacked for fabricating quotes, but later made a name for himself as Brussels correspondent for The Daily Telegraph.
Johnson was among the first to peddle what have been collectively termed "Euro-myths" about bans on bendy bananas -- a style of reporting about the EU that became a staple of the British press.
He was elected to parliament in 2001 and was sacked as Conservative arts spokesman for allegedly lying about an extra-marital affair.
But he bounced back and in 2008 -- by then known nationwide as simply "Boris" -- was elected mayor of the multi-ethnic, usually Labour-voting capital.
He was re-elected in 2012 and oversaw the Olympic Games that year, memorably getting stuck on a zip-wire while celebrating Great Britain's first gold medal.
Johnson has drawn on his experience as mayor to show he can deliver, pointing to falling crime, house-building projects and his work with business.
However, sceptics also note expensive vanity projects such as a doomed "garden bridge" as proof his grand visions do not always translate into good governance.
He returned to parliament in 2015 as MP for a northwest London suburb, promising to oppose the expansion of Heathrow Airport.
But as foreign minister, Johnson missed a key parliamentary vote on the infrastructure project after hastily arranging a trip to Afghanistan.
- 'Least successful' diplomat -
May's decision to put Johnson in the Foreign Office was viewed as a canny move after she took power -- to keep him close but at arm's length.
But it risked being deeply awkward. He once wrote about the Commonwealth's "flag-waving piccaninnies", among other lurid turns of phrase.
In office he also made some major errors, notably in suggesting that a British-Iranian woman held in Tehran on sedition charges may have been training reporters.
The family of Nazanin Zaghari-Ratcliffe strongly denies this and fears that the remark jeopardised her case.
The Chatham House international affairs think-tank concluded Johnson was Britain's "least successful" foreign minister since World War II.
"Where gravitas and grasp of detail were needed Johnson supplied bon mots," it said.
Johnson quit in July 2018 over May's Brexit strategy, although he later voted for her divorce deal as the best way to get out of the EU.