Relations between Boris Johnson and his party's leadership have reached breaking point with new and potentially damaging divisions over the mayor's plans for London.
Behind the scenes, Tory high command has decided against three specific policy proposals that Johnson has demanded for the party's next election manifesto. The first is Johnson's backing for Crossrail. Tory opposition to this will infuriate City financiers, who see it as crucial to London's future.
On this, a spokesman for the mayor told me: "There is a wide consensus around the huge importance of the Crossrail project to the London and UK economy, and construction has already begun." So Johnson is resolute.
The second is Johnson's plan for an estuary airport, and the third is his desire for enhanced mayoral powers. David Cameron is desperate for Johnson to stand for re-election as mayor in 2012, so his fellow Old Etonian does not return to the Commons to pursue the Conservative Party leadership that he still privately craves. Johnson faces a dilemma over whether to continue as mayor or seek a safe Tory seat.
His public attempts to undermine Cameron first emerged last August, when he flatly contradicted Cameron's oft-repeated claim that Britain is a "broken society". Writing in his Telegraph column, which he says provides a "chicken-feed" sum of £250,000, Johnson said: "If you believe the politicians, we have a broken society . . . what piffle that is."
Since then, Johnson has openly opposed opportunistic attempts by Cameron and George Osborne to attack City bonuses. Now Osborne has got his revenge by blocking the mayor's latest ideas. Both, incidentally, see themselves as Cameron's successor. That looks like one to watch.