The race to be London's next mayor is littered with savage expletives and maverick personalities.

So will the rumpled, comic, often foul-mouthed incumbent (Boris Johnson) or his leftist predecessor (Ken Livingstone) who loves his pet newts and admires Venezuela's Hugo Chavez triumph to lead Britain's capital?

One thing is certain when results are announced Friday: Neither is going to be a uber-slick, overly polished host for London's 2012 Summer Olympics.

BIG PERSONALTIES

Boris and Ken _ both known universally by their first names _ clash as frequently with their own party allies as with their rivals.

The Conservative Johnson, 47, is a long time friend-but-rival of Prime Minister David Cameron and produces often-offensive gaffes. Despite an elitist upbringing, Johnson's bumbling style and foul mouth appear to endear him to many.

Livingstone, dubbed "Red Ken" for his left-wing views, also gets in trouble for his sharp tongue. The 66-year-old Labour Party politician once called President George W. Bush "the greatest threat to life on this planet" and compared a Jewish reporter to a Nazi concentration camp guard.

TRANSPORT MODES

The bicycle-loving Johnson pedals around town frequently in business suits or eye-popping riding clothing. Livingstone mingles freely with residents on London's subway, the Underground, to showcase his Mr. Ordinary credentials and his flagship policy was a traffic-busting "congestion charge" to drive into the city center.

POLITICS

Experts claim Johnson, a Conservative Party lawmaker from 2001 to 2008, has a political ace in the hole: an ability to shrug off controversies that would wreck another's career. His calls for looser ties to Europe and lower taxes have cheered grassroots Conservatives. Livingstone has been a stalwart of Labour Party politics for four decades and was once a fierce opponent of ex-Conservative leader Margaret Thatcher.

PRIVATE LIVES

Both men are known for tangled private lives: Livingstone has five children with three women, while Johnson _ married with four children _ was once fired from a Conservative post for lying about an extramarital affair.

OLYMPICS

Livingstone took an energetic role in the bid that delivered the Olympics to London, while Johnson has presided over four years of meticulous preparations. Johnson has offered typically crowd-pleasing advice to Londoners facing rush-hour travel chaos as millions arrive for the Olympics: Head to the nearest pub for a beer.