A plan to expand Heathrow Airport could face rejection because of "dithering and delay", Zac Goldsmith told IBTimes UK this morning (19 October).

The Conservative Richmond Park MP has promised to quit the House of Commons if the government gives a third runway at the West London site the green light.

"Heathrow has always been the default position of successive governments because the company used to be a monopoly with total access to government, and many of those relationships continue today," he said.

"But in addition to the noise, cost and pollution, a green light for Heathrow would mean more years of dithering and delay, and for that reason there is still a strong chance it will be rejected."

Goldsmith, who entered parliament in 2010 and unsuccessfully ran for Mayor of London in May, also failed to rule out running as an independent candidate if he triggers a by-election.

"For my part, I made a promise some years ago, and I will honour it. But for now I am concentrating on winning the arguments," the environmentalist said.

Goldsmith currently holds a majority of more than 23,000 over the Liberal Democrats.

Twickenham MP and fellow Tory Tania Mathias has vowed to back Goldsmith if he runs as anti-Heathrow independent, according to The Evening Standard.

Theresa May has allowed her minister to express "personal views" for a "limited time" on whatever decision the government makes. Ministers are usually expected to maintain cabinet collective responsibility.

The move would allow Foreign Secretary Boris Johnson and Education Secretary Justine Greening to publicly protest if the Heathrow Airport expansion plans gets the go ahead.

"It's right that Ministers will be able to make the case against Heathrow expansion, if that's the option the Government picks," Goldsmith said. "For people like Justine Greening and Boris Johnson, it's a hugely significant issue, and their contribution will be immense."

The government's preferred airport expansion site – either Heathrow or Gatwick – is expected to be unveiled next week. The decision will be made by a cabinet sub-committee.

But May appeared to backtrack on plans to push ahead with the project last night after it emerged the prime minister said parliament may not have a vote on the issue until the winter of 2017/18.

The Airports Commission, chaired by Sir Howard Davies and published in July 2015, backed a third runway at Heathrow.