Boris Johnson will not attend the mayoral cabinet planned by David Cameron in Downing Street, he has made clear to politics.co.uk.
The London mayoral candidate has already indicated his hostility to his party leader's plans for English mayors to get together in No 10, telling the Financial Times earlier this month he would "resist" any "attempt to get mayoralties into a room and control them".
Today he went further, ruling out his presence at any future meeting. Mr Johnson said he would send a City Hall representative in his place.
"I have no particular desire to see the mayoralty of London lumped in with a team of other mayoralties," he told politics.co.uk while campaigning in Croydon.
"I told the prime minister the other day - he can call a mayor's cabinet but I'm not going to it. Mayoralties are organic expressions of people's popular democracy."
Referenda for directly elected mayors are taking place in ten English cities on May 3rd, when Mr Johnson takes on Ken Livingstone's and others for another term in City Hall.
Those which vote 'yes' will then elect their first mayors this November, after which Mr Cameron will be looking to "bring them together so we can swap ideas and experience and initiatives".
Mr Johnson is suspicious of Whitehall's control over local government in general, despite expressing surprise that the London mayoralty had significant powers.
He said the biggest surprise of his four years in power had been "the scale of the executive power that the mayor already enjoys".
Mr Johnson added: "I think the biggest surprise is that a central government should be so generous to the point of foolhardiness in creating a devolved authority of such power.
"The trend towards devolution is going to continue. The idea that central government can manage things in the way it did for much of the 20th century is over."
The prime minister had made clear he intends to continue the coalition's localism agenda, however, in his speech announcing the mayoral cabinet on March 28th.
Mr Cameron said: "We can really make sure that central government is not just helping to deliver these referendums, but is also going to start delivering extra powers, extra resources to those cities and to those mayors so they can get even more things done."
The Conservative candidate has been at pains to distinguish himself from his party leader throughout his mayoralty. He has been a steadfast supporter of the City, called for a referendum on the Lisbon treaty and attacked the coalition's benefit cap proposals.