One sports an unruly blond mop, spouts Latin aphorisms and loves to ride his bicycle. The other is a neat, newt-loving socialist who prefers to travel by subway.
Their contest is an Olympic-size grudge match. Meet Boris and Ken - hometown celebrities known universally by their first names. When the 2012 London Games open on July 27, one of them will stand before billions of television viewers as mayor of the host city.
The incumbent, Boris Johnson, warns that it had better be him and not Ken Livingstone - his predecessor, intense rival and would-be successor.
''Obviously it's an eventuality that I try not to contemplate,'' Johnson said during a break in campaigning for London's May 3 mayoral election. ''And I'm working very hard to make sure that I'm spared by the electoral reaper.''
Whoever wins, London's next mayor will be a larger-than-life figure whose gaffes and idiosyncrasies would have sunk a less confident politician. The winner will oversee a world-class city of 8 million people and a 14 billion-pound ($22 billion) budget.
Johnson, a Conservative, hopes to win a second four-year term while Livingstone, London's mayor from 2000 to 2008, is from Labour - but both transcend the parties they nominally represent.
Livingstone has the greater London ties. He was born and raised in the city, speaks with a nasal cockney accent and has been prominent in local politics since the 1970s.
Johnson, with his rhetorical flourishes and unmistakable shock of hair, is a more quintessentially British character: the erudite upper-class buffoon.
''Boris reeks of the notion of British character for a nation that's self-identified as liking eccentrics and people who are a bit out of the ordinary,'' said Tony Travers, an expert in local government at the London School of Economics. ''Ken is more technocratic - looking and in reality.''
Both men have tied their political fortunes, in part, to the Olympic Games. Livingstone helped lead the bid that brought the event to London. Johnson has presided over four years of preparation for the July 27-Aug. 12 extravaganza.
Livingstone says the Olympics have already proved their worth, by transforming a grim postindustrial patch of east London into the 500-acre (200 hectare) Olympic Park.
''I bid for the Olympics so we'd get the investment in what's the most deprived area in southern England,'' Livingstone said. ''The sporting event is a sort of add-on at the top. It's important to get the most polluted site in London cleaned up and new homes, new transport infrastructure.
''As far as I'm concerned, the benefits of the Olympics - we've had those already.''
Johnson, who has had to handle the logistics of mounting the games, also stresses its legacy of thousands of new jobs and homes. And he is keen to reassure Londoners, and visitors, that he is on top of the two biggest potential nightmares: security and transport.
''Security is obviously a great priority for us and we're making sure everything is in place,'' Johnson said. ''We think the risk level has come down but clearly you can never be complacent.''
And if London's overburdened public transport system seizes up under the strain of so many visitors, he said, ''we think people will get the point, they'll manage and they'll be able to go off, have a beer or whatever it is and absorb the impact.''
That is the typical insouciance from Alexander Boris de Pfeffel Johnson, 47, who was born in New York and is the great-grandson of Turkish journalist and government minister Ali Kemal.
Johnson attended the elite boarding school Eton College and studied classics at Oxford University, where he was - along with Prime Minister David Cameron - a member of a rowdy, aristocratic drinking-and-dining society called the Bullingdon Club.
A journalist who was a member of Parliament between 2001 and 2008, Johnson has combined politics with book writing and frequent television appearances, cultivating an affable persona that has been undermined by periodic gaffes.
The most infamous came when he referred to members of the Commonwealth as ''piccaninnies,'' a derogatory term for black people, and likened his party's internal conflicts ''to Papua New Guinea-style orgies of cannibalism and chief-killing.''
In both cases he apologized. Johnson has largely been able to pass off such stumbles as signs of his unpolished authenticity. Opponents say they are evidence of bigotry at worst, and at best callousness or distraction - Livingstone calls Johnson a ''part-time mayor'' with too many outside interests.
Livingstone, 66, has concentrated on London politics for decades. He led London's local authority during the 1980s until it was abolished by Conservative Prime Minister Margaret Thatcher.
Nicknamed ''Red Ken,'' he became famous for two things - left-wing views and raising great crested newts.
As mayor, Livingstone gained praise with his sure-footed response to the 2005 London transit bombings that killed 52 people and for introducing a traffic-busting ''congestion charge'' to drive into the city center, a policy admired New York City Mayor Michael Bloomberg, among others.
His views on international issues are more controversial. Livingstone once called President George W. Bush ''the greatest threat to life on this planet,'' welcomed hard-line Muslim cleric Yusuf al-Qaradawi to London, and was suspended from his post for a month after comparing a Jewish reporter to a Nazi concentration camp guard.
Livingstone denies anti-Semitism, but his words have alienated many Jewish voters.
Both men are also known for their busy private lives. Livingstone has five children with three women, while Johnson was once fired from a Conservative post for lying about an extramarital affair.
They seem to have a visceral animosity, getting into a shouting match in an elevator after a recent radio debate, with Johnson repeatedly calling his rival an ''(expletive) liar'' for claims about Johnson's tax status.
The dispute ended with the candidates publishing their tax records, which showed that both earn many times more than the average Londoner: 1.7 million pounds ($2.7 million) over four years for Johnson; 342,000 pounds ($540,000) for Livingstone.
Opinion polls give Johnson a slight edge, but indicate a close race. Liberal Democrat contender Brian Paddick, a former senior policeman, is a distant third.
Most questions from voters during the campaign have focused on bread-and-butter issues: crime, housing, public transport. And while voters are divided, few are undecided.
''There's only one choice - Boris,'' said Leigh Nicoll, a lawyer. ''Boris has a pro-business agenda. Ken just doesn't seem that bothered.''
Gerald Coffey, a construction worker, was equally definite.
''Ken would be my favorite,'' he said. ''He's a man to voice his opinion. ... And if he doesn't get his way, at least he'll cause a lot of trouble.''
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Online:
Back Boris 2012: http://www.backboris2012.com
Ken Livingstone: http://www.kenlivingstone.com
Jill Lawless can be reached at: http://twitter.com/JillLawless
