A lack of "enthusiasm" from government officials for plans to dual a stretch of the A1 saw the project "frustrated", it has been claimed.
The scheme to upgrade a 13-mile (20km) section of road between Morpeth and Ellingham was cancelled by the Labour government last year due to projections which suggested it would cost more than £500m.
At an event ahead of local elections on 1 May, Councillor Richard Wearmouth, deputy leader of Northumberland's Conservatives, said his own party had also acted too slowly before being replaced in government.
Councillor Scott Dickinson MBE, leader of the county's Labour group, said investment criteria was "very skewed to the south" of the country.