More bobbies and new buses: Boris's promise to London's voters

Boris Johnson launched his campaign to become Mayor of London yesterday with a bad pun, a series of wisecracks and a malfunctioning video film. But the maverick Tory MP declared: "I reserve the right to make jokes, but be in no doubt that I am deadly serious in asking you to support me."

Mr Johnson is the clear favourite to become the Tory challenger to Ken Livingstone next year in the battle to run the capital. He unveiled a series of populist policy proposals, including more 24-hour policing, boosting home ownership, reforming the congestion charge and encouraging newcomers to learn English.

Senior Tories believe he has the charisma to take on Mr Livingstone, although others fear his gaffe-prone style is bound to land him in trouble. His glitzy campaign launch hit a problem when the sound of a short video film setting out his credentials for mayor failed to operate.

But his speech won applause and laughter in equal measure from supporters as he told them: "I love this city and I want it to be greater still."

He put crime, public transport and affordable housing at the heart of his appeal to the capital's voters. Mr Johnson called for a change in the culture of "casual theft and incivility on our streets" and promised to develop a plan for round-the-clock policing across London. The Henley MP added: "I promise you that, as Mayor, I will be wholeheartedly on the side of the active citizen and against the thugs."

Mr Johnson said he would retain the congestion charge, but make it "fairer and more flexible", design a new "iconic" version of the Routemaster bus, develop air conditioning for the Tube and champion cycling. He attacked builders' "Ceausescu-esque obsession with rabbit hutch dwellings" and pledged to promote shared home ownership schemes.

He criticised Mr Livingstone for signing an agreement with Hugo Chavez, the Venezuelan president, to buy oil from the south American nation. "You won't catch me doing deals with left-wing dictators. Venezuelan slum children are effectively subsidising Transport for London. I say it's completely Caracas," he said.

And he promised to scrap spending by the Mayor on space research, unless "the current incumbent is willing to go into orbit".

He also said he gloried in the different ethnic backgrounds of the capital's residents, joking: "My children have the genetic diversity of a UN peace-keeping force."

Three other Tories – Andrew Boff, Victoria Borwick and Warwick Lightfoot – are standing against Mr Johnson for the nomination.

Mr Livingstone said last night: "Boris Johnson's claim to stand for a liberal, diverse city with improved public services is totally contradicted by his long-term support for the Thatcherite policies which produced squalor in London in the 1990s."

* William Hill have shortened the price of Boris Johnson becoming mayor to 15/8. Mr Livingstone is odds-on favourite at 8/15.