London Mayor Boris Johnson today confirmed he would be seeking re-election for a second term.
The Tory former MP said he wanted to stay on beyond May 2012 because he had "more to do" improving the capital and overseeing the Olympics.
"It is my intention and indeed I have written to seek the nomination to serve as Mayor for another term," Mr Johnson told LBC radio's Nick Ferrari show.
"I have got tough challenges on crime, improving the urban environment. I do think it is a good record so far and I am proud to defend it."
Labour is set to decide whether former mayor Ken Livingstone or ex-MP Oona King will be its candidate for the post later this month.
Mr Johnson said he anticipated facing Mr Livingstone - the man he defeated in the 2008 contest. "I expect they will go for Ken," he said. "The union block vote will go behind the old war horse I suppose."
Asked why he waited so long to declare his intention, Mr Johnson said he had wanted see how key initiatives worked. There was a "certain amount of nailbiting" over the scheme to make thousands of bicycles available for hire across London.
But he insisted: "When I look at the list of things we have got to do, I look at the Olympics, I look at all the prospects we've got to deliver change in London, to make something of the Olympic investment - not just for the site, the whole of east London - all the things that are in prospect. I have only got two years left in this term, and we are going to need to keep going."
Mr Johnson played down his rift with the coalition over its planned cap on non-EU immigration, saying he was merely lobbying for limits to be "thought through" so businesses such as law firms and film companies were not prevented from importing the best talent.
But Mr Livingstone urged voters to punish Mr Johnson for the coalition's assault on public spending.
"I welcome Boris Johnson's confirmation that he will run again in 2012 because he now has a record that means he can be held to account," he said.
"Boris Johnson cannot escape the fact that he has pioneered huge cuts in London and he vigorously campaigned for his Tory colleagues to win the general election, knowing full well the economic policy they would deliver and the damage they would do to policing and transport. The Government's cuts are his cuts.
"For those who want to express their opposition to the cuts and higher fares of Boris Johnson and David Cameron the first opportunity to send a signal that they want something better will be to remove Boris Johnson from office in 2012."
Mr Johnson is set to be officially endorsed as the Tory candidate next month.Reuse content