Labour MP John McDonnell warned the government today that it will face a huge wave of protests if it backs a third runway at Heathrow.
At Prime Minister's Question Time he demanded David Cameron pledge with "no ifs or buts" that there would be no third runway while he led the Tories.
Mr Cameron said that, while he believed there should be a review of airport capacity, "I will not be breaking my manifesto pledge."
Alarm spread among campaigners after third-runway opponent Justine Greening was summarily removed from her job as Transport Secretary in Tuesday's Cabinet reshuffle.
This followed hard on the heels of a Downing Street declaration that an "independent" commission will be announced next week to examine all the options for new runways in south-east England.
Mr McDonnell said the transfer to other posts of Ms Greening (left) and her deputy Theresa Villiers (right) "demonstrates that the government's aviation and environmental policies are being determined by the corporations seeking short-term profits."
The Hayes and Harlington MP declared: "The battle over Heathrow will now once again become the front line of the struggle over climate change.
"Every form of mass protest will be used if the Tories try to come back for a third runway.
"I warn the Tories that they will not know what will hit them."
London Mayor Boris Johnson entered the fray following the Cabinet reshuffle, declaring that the government would be "simply mad" to expand Heathrow.
In a stormy outburst, he accused Mr Cameron of being on the verge of breaking his election pledge to block a third runway at Heathrow.