Boris Johnson has launched a furious attack on George Osborne, accusing him of trying to wreck his chances of becoming prime minister.
Friends of Johnson say he erupted into a tirade against Osborne, after reports that Osborne had asked the London mayor to return to the Commons at the next election.
Johnson was heard to exclaim "Bullshit!" when reading the reports, a well-placed source told the Daily Mail.
"There has been no such conversation," Johnson added. "They are trying to tie me in."
Sources close to Osborne claim that he has told Johnson to stand as an MP in 2015 in an apparent attempt to "call his bluff" over his leadership intentions.
The chancellor is also thought to be assembling a team of allies, ahead of his own possible leadership bid.
The London mayor believes Osborne is trying to make him closely associated with the next Conservative general election campaign, which risks damaging his hopes of winning the Tory leadership after Cameron.
"This is nothing to do with party loyalty and everything to do with Osborne and Cameron trying to destabilise Boris," an ally of the Mayor told the Mail.
"He saw it coming a mile off. They want to make sure that if the Tories lose, Boris gets as much flak as they do and can’t stand as leader as a "break with the failed Cameron-Osborne regime""
"This is a clumsy attempt to con him into doing it, with inevitable claims that he can’t wait for Cameron to fail, or falsely accuse him of disloyalty if he doesn’t stand."
Johnson's allies believe they are trying to trick him into leading the campaign against Ukip's Nigel Farage "because they know it would lose Boris votes in any Tory leadership contest ."
Relations between the two men deteriorated last year, after Osborne decided to accompany Johnson on a long-planned trip to China. Those close to Johnson accused Osborne of "muscling in" on the trip and trying to exclude the London mayor from key meetings.
They also fell out after Osborne failed to inform Osborne of plans to hold this year's fares rise at inflation, a decision that has cost Transport for London millions in revenue.
Conservative chairman Grant Shapps today denied claims of a rift between Osborne and Johnson.
"What Boris does is up to Boris," Shapps told the Andrew Marr show.
Asked whether he would like Johnson to return to the Commons in 2015, he added that he was "doing a fantastic job as London mayor" a role which does not end until 2016.
Johnson is still "genuinely undecided" about when he wants to return to the Commons, sources close to the Mayor have told Politics.co.uk.