Business and council leaders have said they are angry after the government announced a planned upgrade of the A160 at Immingham is to be delayed.
Transport Secretary Philip Hammond said on Tuesday that work would not start on the road until at least 2015.
North Lincolnshire Council and Hull and Humber Chamber of Commerce said they were disappointed and baffled by the decision.
They now plan to take up the matter with the government.
Improvement work on the A160 was due to begin in 2013.
Leader of North Lincolnshire Council Mark Kirk said: "I fear that the scheme has now been effectively kicked into the the long grass. It's a slap in the face for the Humber, no doubt about it.
"We will now be calling an urgent meeting of the region's MPs," he said.
Richard Kendall, policy executive at Hull and Humber Chamber of Commerce, said: "The A160 is a regionally and nationally important infrastructure project, recognised as one of the top priorities in Yorkshire & Humber.
"The decision to delay it is baffling, particularly as it comes just days after the government pledged to support development in ports.
"To cut investment in vital transport infrastructure in this way is to cut economic development - something which we badly need to turn the national economy and the public finances around.
"We will be urgently taking up the issue with ministers and our MPs."