Expansion at Heathrow moved a step closer today as the airports commission shortlisted two proposals for new runways at the London airport.
Under the plans, Heathrow would either build a third runway to the north east of the airport, or lengthen the airport's existing northern runway to allow it to operate as two separate runways.
A third option of expansion at Gatwick is also being considered, but none of the proposals to build a new hub airport by London Mayor Boris Johnson have yet made the shortlist.
The decision risks a major confrontation with Johnson and other senior figures in the Conservative Party who remain bitterly opposed to any further expansion of Heathrow.
Johnson told the Today programme that he rejected all three of the shortlisted proposals and described expansion at Heathrow as "crackers".
"Building another runway in the west London suburbs is completely crackers, it will simply feed the beast," he said.
"My question to the world is why on Earth entrench a huge planning error and expand Heathrow and consign generations to misery when you could go for the right option."
Conservative MP Zac Goldsmith recently threatened to force a by-election and stand on an independent ticket if the government backs expansion at Heathrow. He said it would be an "off the scale betrayal" for David Cameron to reverse his manifesto pledge to oppose a third runway.
He blames the Chancellor George Osborne for the government's apparent reversal in their oppposition to Heathrow expansion.
"George Osborne is not a free market Tory: he is a corporatist," he wote on Twitter this morning. "A taxpayer-funded Heathrow monopoly therefore fits his world view."
A fourth option of building a new airport on the Isle of Grain will also be considered by the commission for future inclusion on the shortlist. However sources close to the discussions suggested that while it "was still in the running" it was "a long way behind the frontrunner."
Davies is thought to have come under pressure not to completely rule out a new estuary airport in order to avoid an all-out confrontation with Johnson and others.
However, the report is highly critical of the proposal as it stands.It questions whether the scheme could be either financially or environmentally viable and suggests it would lead to the closure of both Heathrow and London City Airports.
Davies told the Today programme that while proposals for expansion at Heathrow were "buttoned down" a new airport in the Thames Estuary would be a "much more extensive proposition".
The commission calculated that a new airport at Grain would cost up to £112 billion. Davies said that more work needed to be done to consider whether it was "a price of anywhere near reasonable".
Johnson has previously put the cost of a new hub airport at almost half that figure and claimed today that it could be "relatively easily financed by international investment."
Johnson said that he would continue his fight to prevent Heathrow expansion, but appeared to rule out resigning over the issue."I believe in going on and winning fights, not in flouncing out," he said.