The business case for a high speed rail link between London and Birmingham "does not stack up", Buckinghamshire County Council has said.
It is hosting a summit about three proposed routes, all of which would go through Buckinghamshire.
Invited campaign leaders will help create a response to government plans.
Valerie Letheren, cabinet member for transport, said any business case did not justify the "intrusion" in to Buckinghamshire's countryside.
The meeting in Aylesbury on 18 June will be jointly hosted by the county's four district councils.
Members of the public will not permitted, but the outcome of discussions will be made known afterwards, the council added.
A further summit will be held later in the year to concentrate on the environmental impact of the routes.
Ms Letheren said discussions will help create an "educated and reasoned response" to the plans.
"By joining up our thinking and expertise we can offer an educated and reasoned response why the business case does not stack up and does not justify any intrusion into Buckinghamshire's unique and beautiful countryside," she added.