London Mayor Boris Johnson warned that middle income families were feeling "utterly and understandably ignored", as he prepared to address the Conservative conference in Birmingham.
Mr Johnson's arrival in Birmingham threatens to overshadow events in the conference chamber after polls suggested he outstrips Prime Minister David Cameron in public popularity thanks to his re-election as mayor and his much-applauded handling of the summer's Olympic Games.
He once again used a press article to highlight apparent differences with the Government, following earlier clashes over Europe, the proposed third runway at Heathrow and funding for infrastructure projects in the capital.
Writing in the Daily Telegraph, Mr Johnson called for more help for the "struggling middle" - working families with incomes ranging from £30,000 to £64,000 - particularly regarding issues such as housing.
"They are not being helped," he wrote. "They are feeling utterly and understandably ignored. It is time to help them."
Mr Johnson on Sunday sought to play down speculation that he is positioning himself to succeed Mr Cameron as Conservative leader and Prime Minister, insisting that it was a "distraction" from his job as London Mayor. But in an interview for Pienaar's Politics on BBC Radio 5 Live on the opening day of conference, it was notable that he avoided ruling out a future bid for the party's top job.
Asked if he believed Mr Cameron was doing a better job as PM than he could, he would only say that the question was "unverifiable".
And challenged over whether he harboured ambitions to be PM, he said that what he wanted to be was mayor "certainly for the next few years", adding: "After four years are up, heaven knows. I will be an old man."
Mr Cameron was the best man to run the country "now", he said, adding that it was "perfectly natural" for the media to construct a narrative in which the two men were in competition, as his position as a representative of London's interests "inevitably" brought him into conflict with the Government.
"My function is to run London, I have been elected to do that, and David Cameron is overwhelmingly the best man now to lead this country, to clear up the mess that Labour left, and I think he is doing a bang-on job," said Mr Johnson.