Goldsmith, the MP for Richmond Park, is widely seen as the front-runner for the Conservative candidacy in a field that also includes London MEP Syed Kamall, deputy mayor for policing Stephen Greenhalgh and London Assembly member Andrew Boff.
An environmentalist who has been among the most-vocal opponents of Heathrow expansion, Goldsmith said in 2008 that he would resign as an MP if the government agreed to build a new runway in west London instead of at Gatwick or another airport. His resignation would trigger a by-election in which he could stand as an independent candidate.
After the Airports Commission recommended a third runway at Heathrow in July, Goldsmith repeated his threat to step down if the government signed off on it. Prime Minister David Cameron has said that the government will decide whether to accept the commission’s recommendation by the end of the year.
But at a mayoral hustings event late last night with the other Conservative mayoral candidates, Goldsmith clarified his position, saying that while he would resign as an MP if the expansion were approved, he would remain a Tory and stay in the mayoral race.
“It’s a promise that I would absolutely be obliged to honour,” Goldsmith told an audience at the Institute of Directors.
“I would not resign from the Conservative party. I would not resign from the mayoral contest.”