As minister for Europe, Mr Lidington would be expected to side with the Government on any whipped vote in the Commons.
He said that with only around 50 MPs directly affected by the route, it was likely the battle against high speed two will have been lost if a bill ever goes before Parliament.
But when asked if he would still vote against a bill to build the proposed route, he said: "At that stage I would consult with my constituents.
"You are asking me about a hypothetical route at the moment but I have said consistently if it came down to it I would vote against the route as proposed."
He admitted losing his ministerial job 'might be the choice I face'.
"But I have a very positive outlook and would look at the legislation in front of me and at the moment we are talking hypotheticals."
He said he was free to criticise HS2, although like any other minister he is unable to speak or ask questions in the Commons.
"I am personally against it (HS2) and there is nothing to stop me representing the views of my constituents.
"When I saw (transport minister) Theresa Villiers two weeks ago I put to her very plainly the strength of feeling and all the arguments against HS2."
The Aylesbury Conservative party has launched an internal high speed action group.
See
Voice of the PaperFor much more High Speed Two, pick up a copy of The Bucks Herald, out today.