Every voter in London will be able to have a say in choosing the Conservative candidate to be the capital's mayor.
Mr Cameron says he wants every Londoner to have a say
David Cameron hopes the unique process - involving hustings and then text and phone voting - will boost the Tories' chances in the 2008 election.
London-based party members can put their names forward to be candidates and head-hunters will also be used.
In an effort to avoid the vote being rigged there will be a "modest" charge for every vote cast.
Mr Cameron said: "Too many people are fed up and disillusioned with politics. I hope that doing things differently will fire the public's imagination and get them talking and thinking about politics again."
He said the aim was to give "every Londoner a say... later in the year, we will be holding a series of public meetings across the capital so that Londoners can quiz potential candidates face to face.
"Then every Londoner will be able to vote by text or phone on who should be the Conservative candidate for the capital's top job."
REQUIREMENTS OF A TORY CANDIDATE:
To be an EU or Commonwealth citizen
Aged 21 or over
A member of the Conservatives
A registered voter in Greater London
A resident or land owner in Greater London
Working in Greater London
A selection panel will assess all applications with candidates vetted for their suitability and draw up a shortlist.
Candidates cannot spend more than £100,000 from the time they submit their applications, and individual campaigns cannot accept more than £20,000 from a single donor.
Tory chairman Francis Maude conceded that there were "risks" of manipulation by non-Tory voters.
But he added: "When people vote, it'll be on the basis of a modest premium - so when you exercise your vote there will be a small part of the cost which actually goes to defray the Conservative Party's costs of running the election.
"So if anyone wanted to go in for massive manipulation they would be enriching the Conservative Party, to a limited extent, and I think that's a bit of a disincentive to our opponents."