Building work on the £1.1bn M4 relief road south of Newport should start as soon as possible, the city's former council leader has said.
The Welsh Government wants to build a 14-mile (23km) motorway between Magor and Castleton which would open in 2021.
A public inquiry is being held into the plan and councillor Matthew Evans wants "urgency" from the Welsh Government in resolving outstanding concerns.
Mr Evans will put forward a motion to Newport's full council on Tuesday.
"This council supports the black route proposals for the M4 relief road," said the motion from Mr Evans, a Conservative candidate for the 2016 Welsh assembly election.
The Welsh Government planned to start construction of the six-lane relief road in 2018 but a public inquiry, which started in February, is still ongoing and will reconvene on 5 December.
Inspector William Wadrup's report could take up to six months following the conclusion of the inquiry.
The Welsh Government said the current M4 around Newport "does not meet modern motorway design standards" and was not fit for purpose.
Welsh companies, who have backed the project, said traffic congestion around the Brynglas tunnels is affecting businesses.
But wildlife organisations have said a relief road - between the current M4 junction 23A and 29 - would "rupture" the historic Gwent Levels, described as "Wales' own Amazon rainforest".
Objectors to the scheme include Natural Resources Wales, the National Grid, Friends of the Earth, the owners of Newport docks and the RSPB while Newport and Monmouthshire councils have supported the plan.
Catherine Linstrum, chairwoman of the Campaign Against the Levels Motorway (Calm) said the group was concerned by the motion.
She added: "The new road will just encourage more traffic onto the roads, increasing congestion across south Wales.
"The city will also suffer economically as the proposed route will bypass Newport on both sides, taking goods, services and jobs to Bristol and Cardiff, whilst also wiping out the businesses that lie directly on the line of the new road."