Boris Johnson has been described variously as a "clown" and a "formidable opponent" by his two main adversaries.
His newspaper columns and regular appearances on the TV show Have I Got News For You have made him one of the most recognisable figures at Westminster.
But the 43-year-old's high profile has been achieved at a price, with bad publicity over rumours of affairs and a series of gaffes.
He was forced to apologise after an editorial in The Spectator magazine, which he edited at the time, said the city of Liverpool "wallowed in victim status" in the wake of the killing of Iraq hostage Ken Bigley.
He also said sorry to Papua New Guinea after linking the island state with "cannibalism and chief-killing".
And he was fired from his front-bench job by former boss Michael Howard for denying an extra-marital affair with Spectator colleague Petronella Wyatt.
But the close friend of Tory leader David Cameron has a habit of bouncing back from such setbacks.
He won a cult following among students and the respect of many university and school leaders after becoming the Conservative's higher education spokesman.
When he stepped down from that post to take on.....continued below
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the mayoral challenge, some commentators predicted his gaffe-prone nature would make him destined to lose.
Indeed, his Liberal Democrat opponent Brian Paddick said of him: "We need a serious ambassador for London to be our mayor - not a clown."
But Labour's Ken Livingstone never underestimated the threat.
The Labour mayor described Mr Johnson as "the most formidable opponent I will face in my political career".
And that assessment would appear to have been an accurate one if recent evidence putting him ahead in the polls is anything to go by.
Since being chosen as the Tory candidate for London mayor, he has made transport one of his key policy areas, launching a ferocious assault on the capital's bendy buses and praising the old Routemasters.
Like his boss Mr Cameron, he is a keen cyclist who regularly bikes into work.
He has also fallen victim to bike thieves and has some typically pithy ideas about how to deal with them.
"If I had my way I would plant decoys in a whole lot of bicycles across the borough and in the evening I would send Navy Seals in through the thieves' windows and show them what it's all about," he once said.
The Tory candidate, whose full name is Alexander Boris de Pfeffel Johnson, was educated at Eton and Oxford. Twice-married, he has two sons and two daughters.
After a short stint as a management consultant, he joined The Times as a trainee journalist but was sacked for making up a quote.
He joined the Daily Telegraph in 1988 and spent five years as the newspaper's correspondent in Brussels covering the European Commission.
He has been MP for the Tory safe seat of Henley since 2001.
Copyright P.A.
