The dual carriageway drops to a single one for about three miles
Transport minister Rosie Winterton has been asked to give priority to the development of a bypass around an accident blackspot in Gloucestershire.
The A417 dual carriageway drops to a single one at Nettleton Bottom, an area known locally as the "missing link".
The county council wants a bypass around the bottleneck, but some local residents are pushing for a tunnel.
The authority has written to the minister, pressing for financial support for a solution.
The section is the only stretch of single carriageway on the M4/M5 link road from Swindon to Gloucester.
Campaigners have called for an end to the regular congestion and crashes which blight the route.
But the government has said it is not 'vital' enough to receive national or regional funding.
The council's letter to Ms Winterton said: "Last month, almost exactly 10 years since the dual-carriageway was opened, a head-on collision on the only stretch of single carriageway caused the death of one local man.
"The three-mile stretch of road regularly makes national travel headlines - causing massive congestion when it snows, when it's icy, when there's an accident, when there's an overturned lorry.
"It's the major trunk route for heavy goods vehicles travelling from mid-Wales, Gloucestershire and Worcestershire, to Swindon, London and the south coast seaports."
The Highways Agency estimates a new link road would cost about £250m.
The county council said this could not be met from regional funding without seriously affecting other transport schemes in the South West.