Critics of the Norwich Western Link have condemned "cheap" tactics as councillors are urged to pledge their support for the scheme.
The divisive road link between the Northern Distributor Road and the A47, west of Norwich, has come back into the spotlight as support for the project appears to waver.
Conservative MP Jerome Mayhew has written to Broadland District Council to request they confirm their "unequivocal" backing of the scheme.
This is because some cabinet members are now "openly against the delivery of this road," he added.
campaign group Stop the Wensum Link, has strongly criticised the gesture and accused Mr Mayhew of "cheap posturing and divisive games".
David Pett, fromHe said: "The facts strongly suggest that Norfolk County Council must halt the Northwest Link project. The escalating costs and the potential long-term burden on council taxpayers, the adverse climate impacts, including flooding and carbon emissions, are all alarming.
"We expect the Broadland cabinet is well aware of these issues too and will not simply follow the extremely risky Conservative line to unequivocally endorse the road project."
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READ MORE:Conservative councillor Stuart Clancy will also ask the full council to confirm their support at a meeting tomorrow, in response to Mr Mayhew's letter.
Broadland is run by a coalition of the Liberal Democrats, Labour and Green parties, led by Lib Dem councillor Sue Holland.
Mr Clancy will request that Broadland write to Norfolk County Council and urge that they "progress this important infrastructure urgently, to avoid further costly and unnecessary delays."
The road must still secure planning permission after the government pledged to give County Hall £213m towards the project.
This leaves a large funding gap for the 3.9-mile road, estimated to cost £274m.
If it does secure planning permission and get through a potential public inquiry, work could start in summer 2026, with the road open in 2029.
Supporters of the scheme say it will be a boost for Norfolk's economy and act as a solution to rat-running in the area.
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