A study is to be carried out into the possibility of building a bridge over the River Severn in Gloucestershire.
A second Severn crossing was completed in 1996 and cost £300m
The county council wants to look at locations for a new crossing on the stretch of river between Gloucester and Sharpness, and weigh up the costs.
Cllr Stan Waddington (Con) said: "If this study shows there is potential, it would be many years before another crossing would be built."
Liberal Democrat county councillors dismissed the plans as "a pipe dream".
The council is planning to commission a study within the next 12 months. It would examine how a bridge would ease congestion on roads between the Forest of Dean and Gloucester.
Mr Waddington said the council had pledged to undertake a "pre-feasibility" study as part of its local transport plans.
"At this stage, we are not committing to building another Severn crossing in Gloucestershire," he stressed.
Councillors from a number of district, town and parish councils in the county have formed a Third River Severn Committee to campaign for a new bridge.
Cllr Bill Hobman (Lab), from Lydney Town Council, said a new rail and road bridge could be built on the site of a former railway crossing between Sharpness and Lydney.
'Not the answer'
"I believe most people would be in favour of an additional Severn Crossing," he said.
But Liberal Democrat councillors on the county council issued a statement which said a new bridge would not tackle traffic congestion problems around Gloucester and Cheltenham.
Cllr John Cordwell (Lib Dem) said: "The county needs solutions to traffic congestion now and in the next few years.
"The pipe dream of another Severn crossing, which would cost tax payers hundreds of millions of pounds and not be built for a generation, is not the answer for commuters and businesses in the Severn Vale."
The Severn is spanned by two bridges near Bristol, some 20 miles south of Sharpness. The second bridge opened, in advance of schedule, in 1996 and cost £300m.