The Prime Minister is today expected to put High Speed 2 at the heart of the Government’s growth agenda and confirm the line will be extended to Leeds and Manchester.
It could spark anger in Oxfordshire and Buckinghamshire where the outcome of a legal challenge into the project is still to be made.
It's claimed the Government failed to properly consult on the scheme.
In a speech Mr Cameron will say HS2 is going ahead and will be the most important project in the UK to create jobs and boost the economy. He is attending a Cabinet meeting in the north where he is expected to make the comments.
Those opposed led by Buckinghamshire and Oxfordshire County Councils say the scheme will destroy large parts of The Chilterns.
It would link London and Birmingham and then go on to Leeds and Manchester. The cost is £32bn.
It would pass close to Wendover, Aylesbury, Bicester and north of Banbury.
More top news
Simon's Blog - All Creatures Great And Small!
Tuesday night's weather with Simon Parkin
Tuesday afternoon's weather with Simon Parkin