MP Mary Macleod has thrown her weight behind a second runway at Gatwick, saying Heathrow expansion is "not politically deliverable".
The Brentford & Isleworth MP said more aviation capacity was needed in the UK and Gatwick was the best place to deliver that.
Ms Macleod has always opposed expansion at Heathrow but this is believed to be the first time she has gone on the record with her support for a second Gatwick runway.
The Tory politician was among the campaigners to descend on No 10 this week to remind Prime Minister David Cameron of his pre-election promise not to allow a third runway at Heathrow .
She said she had backed Gatwick's plan for a second runway in her submission to the Airports Commission, which is considering rival expansion bids from Heathrow, Gatwick and the independent body Heathrow Hub.
"I feel we do need an increase in aviation capacity and that should take place at Gatwick," she told getwestlondon . "Building a second runway at Gatwick is cheaper, simpler and politically deliverable. It could be done at very little cost to the taxpayer and it's a solution you could almost start implementing tomorrow.
"I don't think Heathrow expansion is politically deliverable. There will always be hundreds and thousands of people around Heathrow who say they don't want more noise or traffic.
"Expanding Gatwick also delivers competition, which will hopefully lead to improvements at both airports. At the moment it feels like there's a monopoly for Heathrow.
"I would also push for better transport links between Stansted and London so more people see that as an option."
Ms Macleod's position is in contrast to that of her Conservative party colleague Simon Nayyar, who is standing in Feltham and Heston . He has previously said he is " very receptive" to Heathrow expansion .
The Airports Commission's public consultation on the options for expansion closed on Tuesday (February 3) and the group, chaired by Sir Howard Davies, is due to announce its recommendations this summer.
Ruth Cadbury, Labour candidate for Brentford and Isleworth, this week said she had reiterated her opposition to Heathrow expansion in her submission to the commission.
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