Ministers have been urged to commit funding to further improvements on the A47, including an extension of the dual carriageway section in West Norfolk.
The borough missed out on investment when a £300 million programme of works was announced by the government before the last general election.
But now, the A47 Alliance, a campaign group of political and business leaders, has set out its priorities for the next stage towards its goal of turning the road into a full dual carriageway.
The group has put forward four major projects, including dualling the section from Tilney All Saints to East Winch.
That project would also involve dualling the Hardwick flyover at Lynn.
And the group claims these works could even be done between 2020 and 2025, if the government commits to funding them now.
Alliance chairman, Martin Wilby, said the current programme of projects, on which building work is not due to start for another three years, were “a good first step”, but insisted full dualling is still their aim.
He said: “These improvements are crucial to improve the A47.
“It is the major route across East Anglia and for too long businesses, residents and visitors have had to put up with an inadequate, unreliable route.”
Vice-chairman Graham Plant added: “The A47 is the major route that connects our region to the Midlands and the north, so it’s vital that we maintain pressure on getting the road improved.”
Public consultations are due to be launched shortly on the previously announced programme of works, ahead of an expected start of construction work in 2020.
The group’s other new priorities include further dualling works between the Acle Straight and Yarmouth and on the stretch from Guyhirn to Wisbech.
They are also seeking further junction improvements in the Wisbech and Peterborough areas. The Guyhirn roundabout is on the list of projects announced in late 2014.
Officials are now planning work to canvass wider public support for their aims and are hoping to hold talks with ministers to press the case for wider improvements.
Richard Blunt, West Norfolk Council’s cabinet member for development, who represents the borough at the alliance, said: “I am delighted that the A47 Alliance have recognised the need to upgrade the A47 between Tilney and East Winch including dualling the Hardwick Flyover.
“I will be supporting the alliance to lobby government to ensure this next phase of development of the A47 gets the funding needed to improve this much needed upgrade, which will support the future economic growth of Norfolk.”