LONDON (AFP) - Boris Johnson came close but failed to deliver Brexit by Oct 31. Now Britain's prime minister faces a legacy defining election that will test all of his campaigning skills.

The mop-headed politician managed in three months to do something his predecessor Theresa May failed to do in three years by securing a Brexit deal that at least earned the preliminary support of parliament - until MPs derailed his timetable.

Johnson had pledged he would rather be "dead in a ditch" than tolerate another extension but was forced to accept the EU's extension until Jan 31.

Despite the setback, Johnson wants an election to break out of the political impasse and end what he called "parliamentary dither and delay" even if his future rests on a knife-edge.

A majority victory would make Brexit resolution easier, securing him a permanent legacy among the country's most influential leaders, including his hero Winston Churchill.

Defeat, however, would consign him to the history books as one of Britain's worst prime ministers.

Johnson took over from the stern and increasingly gloomy May in July following a brief stint as foreign minister and eight years as London mayor.

One scandal erupted even before he moved in to Downing Street when a newspaper reported that a neighbour had called the police after hearing Johnson row with his partner.

That soon blew over and Johnson stormed his way to victory in a Conservative party leadership race during which he made a "do or die" promise to deliver Brexit on Oct 31.

'WORLD KING'

Johnson surprised both allies and foes by returning from Brussels earlier this month with a new deal, and defied the odds by clearing the Bill's first hurdle in parliament.

"He is colourful (but) with a strategic vision," French President Emmanuel Macron said after the remaining 27 EU leaders signed up to Johnson's Brexit deal.

"Those who did not take him seriously were wrong."

Although he failed to get his political agreement ratified immediately by parliament, Johnson's efforts appear to have helped heal wounds with MPs within his own party.

Opinion polls now suggest the Tories are more united that the main opposition Labour party under Jeremy Corbyn, as the parties gear up to start campaigning.

But his main challenge will not be Corbyn but fending off arch-eurosceptic Nigel Farage, who will focus on compromises in his deal and his failure to meet the Brexit deadline.

Johnson has earned a reputation as a formidable campaigner, with his outsized personality helping him earn shock wins in the London mayoral race and as the figurehead of the 2016 Brexit referendum.

But his bumbling upper class schoolboy persona and colourful turns of phrase has contrasted with criticism for repeated gaffes, offensive comments, extra-marital affairs and accusations of lying.

'ONE-MAN MELTING POT'

Johnson never talks about his personal life and instead uses his blunders to burgeon a man-of-the people image at odds with a life of privilege.

Alexander Boris de Pfeffel Johnson was born in New York in 1964 into a high-achieving family of future politicians and media personalities.

According to his sister, Rachel, as a child he once aspired to become "world king".

He instead graduated the elite Eton boys school and Oxford University to become a journalist for The Times - a job he promptly lost for making up a quote.

His subsequent time with The Telegraph saw Johnson establish a new genre of reporting: outrageous stories from Brussels about EU regulations that he often either invented or purposely misread.

But these tales about alleged bans on bendy bananas were innocent compared to his later characterisation of Muslim women wearing burkhas as looking like "letterboxes".

He also referred to Africans as "picaninnies" in a newspaper article, but claims this was written in satire, characterising former prime minister Tony Blair's view of the continent.

Johnson, whose great-grandfather Ali Kemal was briefly interior minister in the last grand vizier of the Ottoman Empire's government, rejects accusations of racism.

He also points to his two successful terms as mayor of liberal London.

"I'm the most liberal Conservative PM in decades," Johnson, who once described himself as a "one-man melting pot" of Muslim, Jewish Christian heritage, reportedly told a Cabinet meeting last month.

Those who know him say Johnson is convivial and an instinctive leader who makes up for a lack of strong personal convictions with a keen ability to read political headwinds.

"Which raises the question: why has the Conservative Party leased itself to a man without ideological moorings?" The Times newspaper asked last month.