Cameron's star player, London Mayor Boris Johnson, could be a liability
Bicycle-riding London mayor, considered a 'star player' by British prime minister, could also cause trouble for him and their fellow Conservatives
Johnson, a Conservative like Cameron, has demonstrated voter appeal by winning two terms as mayor in a city dominated by the opposition Labour Party. He also runs the risk of distracting from the Tory campaign as speculation mounts over his desire to succeed Cameron as party leader - and possibly as premier.
Cameron welcomed Johnson's decision, even though it is likely to reignite speculation about his future as leader.
"Great news that Boris plans to stand at next year's general election. I've always said I want my star players on the pitch," Cameron, who was holidaying in Portugal with his family, said on Twitter.
A YouGov poll in June showed that voters see Johnson as the person who would make the best leader if Cameron stepped down. Johnson had repeatedly shrugged off suggestions of loftier political ambitions, once declaring that he had about as much chance of becoming prime minister as being reincarnated as an olive. Asked in 2010 whether he could one day become the country's prime minister, Johnson said: "I'm more likely to be decapitated by a Frisbee or locked in a disused fridge."
The bicycle-riding mayor, who made his name as a journalist and television panel-show presenter, has an appeal that goes beyond traditional Conservative supporters. His instantly recognisable shock of blond hair, unpredictability and off-the-cuff comments have won him backers among a public alienated by traditional politicians.