Pressure on Cameron rises from Tory party ranks over Heathrow plans DAVID Cameron is under increasing pressure from within his own party amid reports of backbench MPs plotting against him and claims that London mayor Boris Johnson could be set for a return to Westminster to challenge the Prime Minister. The moves against Mr Cameron come as he faces rising anger in the Conservative ranks in the Commons over controversial plans for a third runway at Heathrow airport - which Mr Johnson also opposes. The Prime Minister could also face discontent from senior Tory figures moved from their positions in his reshuffle, which saw the removal of Justine Greening, a fierce opponent of the third runway, as transport secretary. Senior Tory backbencher Colonel Bob Stewart yesterday revealed he was approached by two party colleagues to consider mounting a "stalking horse" leadership challenge against the Prime Minister. Col Stewart said he told the rebels to "get lost" and rejected the idea as "silly," as he insisted that he remained loyal to Mr Cameron, who he cited as "the reason I came into politics." Tory MP Zac Goldsmith is reported to have offered his safe seat to Mr Johnson to hand him a platform to challenge for the party leadership and oppose any move to revive the plans for Heathrow. Mr Goldsmith is said to have made the offer to resign his seat in Richmond, south-west London, and let the city's mayor contest it, during secret talks with Mr Johnson on how to kill off government moves to expand Heathrow. The prospect of parachuting Mr Johnson into parliament could trigger a mass revolt against Mr Cameron and pave the way for a leadership challenge by the mayor before the next general election. Multi-millionaire Mr Goldsmith confirmed he had met Mr Johnson to discuss how best to campaign against a third runway after a commission was launched to examine ways to expand airport capacity. It will report in 2015. Mr Goldsmith said: "We compared notes on Heathrow to see what we could do to kill off the third runway. We covered all sorts of possibilities. I would do anything I need to deliver to my constituents what I said I would. However, Mr Johnson dismissed suggestions that he could cut short his mayoral term just months after being re-elected. He said: "I've said, as I said in the election about a billion times, being mayor is the best job in British politics and it's what I want to do." A Downing Street spokesman last night declined to comment on the reports of rising internal pressure on Mr Cameron.