Mr Blair has won over sceptics, widely believed to have included his environment spokes-man, Frank Dobson, and will today say he regards the idea of directly elected mayors as a key way to revive local democracy.
Although he has floated the idea before it was only briefly mentioned in the document on London published by the party last week and there has been strong opposition from some council leaders. Mr Blair will now go significantly further in his speech to a conference on the future of the capital in making it clear that he wants the idea fully developed in time for inclusion in the general election manifesto.
The idea comes in the wake of leaks suggesting that at least one government minister has become converted to the idea of a wider elected authority for London. In a letter to the Downing Street Policy Unit, the minister proposes that the wealthy City of London Corporation - which Labour would preserve - should disappear under plans for a new central elected authority.
Two ministers with London constituencies have denied writing the letter. But according to the leak the anonymous minister has broken ranks with Tory policy with proposals to counter Labour's plans, saying they would "give us something fresh and ... refresh our commitment to local government".
t A new call for Labour's plans for Scottish devolution to be ratified by a referendum is made by the left-of-centre Institute of Public Policy Research today. The IPPR also calls for the number of Scottish Westminster MPs to be reduced and Secretary of State for Scotland to be abolished in return for the creation of a Scottish Parliament.