He will have to leave his Richmond Park seat to become London Mayor but timing is important to the Tory Party.
In 2009, in the run to the 2010 General Election, David Cameron said “no ifs, no buts” to a third runway at Heathrow.
That bold statement has haunted Cameron ever since.
In July 2015 the independent Airports Commission said "the economic case for Heathrow was so compelling it blew its rivals away."
Cameron promised a decision by Christmas 2015 but is back pedalling again.
Five years after an election win there is a big push for an expansion at Heathrow or another southern England airport but Cameron seems unable to act apart from to shuffle uncomfortably.
The Mayoral election and Zac Goldsmith are playing a part in Cameron's unease but then there is the issue of local people.
Air quality monitors already show that pollution around village properties near Heathrow break current legal requirements.
Residents face some tough times; some properties could be bulldozed to make way for a third runway; others including properties in London will experience an increase in, if not excessive, levels of pollution.
As Cameron is being pushed to make a decision on the third runway a global climate change summit in Paris will wrap up this weekend.
In so many ways that summit is a mockery.
The runway and Heathrow or elsewhere will be determined on business and political needs, demands and money; we the little people will not be part of the equation.
How Cameron can attend a climate change summit as residents near Heathrow are being poisoned by excessive pollution is yet more insanity.
A third runway is long overdue or is it?
Perhaps it’s time has been and gone; as instability spreads across parts of Europe and the Middle East expect a downturn in British tourists wanting to travel away from the UK for a vacation.
A third runway may have other uses but as tough times get tougher incoming tourists may also reduce in number.
At the Mail Online - Heathrow third runway decision could be pushed back even further admits transport secretary as BA threatens to move base to Europe
And as ITV News puts it - Heathrow expansion: No ifs, no buts - now it's a maybe