Fears have been raised that Norfolk "is not on the radar" to get millions of pounds more for further dualling of the A47.
And angry council leaders are sending a message to the government that it is not acceptable that the road could miss out on more money, in favour of smaller schemes.
A new report by government company National Highways - which ministers will use to decide which road projects to fund between 2025 and 2030 - acknowledges the importance of the A47.
But it also states that, for the rest of the decade, new enhancements would "have a greater focus on smaller interventions".
That approach does not mesh with the long-standing campaign by Norfolk County Council and the A47 Alliance to get full dualling of the road, including the Acle Straight.
The alliance - made up of council and business leaders - is drawing up a response.
Graham Plant, chairman of the A47 Alliance and Norfolk County Council's cabinet member for highways, infrastructure and transport, said: "We are not happy that there are no A47 schemes in the third road improvement strategy and we will be sending that to the government.
"We are not on their radar. We are not going to get anything if we sit on our hands and wait for National Highways to do it, because that is not going to happen.
"We need to lobby our MPs because that is the only way we will get anything."
READ MORE: Norfolk A47 dualling decisions in hands of High Court judge
The region was awarded £300m in the first round of investment in 2014.
But the three biggest Norfolk projects - the revamp of Thickthorn junction, plus dualling from Easton to North Tuddenham and Blofield to North Burlingham - were only granted development consent last year.
Work has yet to start, after climate activist Andrew Boswell took the matter to the High Court, claiming granting of consent was unlawful, because the cumulative environmental impact of the schemes had not been properly assessed.
The judge's decision is awaited.
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