Inquiry backs M4 relief road, Alun Cairns understands
The Welsh secretary has said he understands a report from a public inquiry into an M4 relief road is in favour of going ahead with the scheme.
Alun Cairns warned failing to build the road, south of Newport, now could delay the project for more than a decade.
The inquiry began in February 2017 and finished taking evidence in March 2018.
A Welsh Government spokesperson said: "Necessary due diligence is ongoing on what would be a significant infrastructure investment for Wales."
Mr Cairns's comments came after council leaders and 90 firms urged Welsh ministers to start the project.
He told BBC Wales: "If we don't build the road now the road won't be built until 2031 at least.
"The reason I say that is that it will take around five years for another first minister - that is the indication that Mark Drakeford has given [to remain in the job]."
"There will then be the new need for a public inquiry and that will take 18 months or so, then there is a five year build programme so it will be 2031 before a road is built if it's not built now," he added.
The Welsh Government previously said officials were analysing a report from a public inquiry into the planned 14-mile (23km) relief road, and a decision will be made when advice has been prepared.
"The money [to build the road] is available, the recommendation from the inspector I understand is in favour - naturally we've got sensitive environmental issues to look after but this is a time where we need a positive decision for a major infrastructure project in Wales," Mr Cairns said.
Assembly members have been promised a vote in the Senedd on the £1.4bn project, and there remains cross-party political opposition to the scheme.
Business leaders argue the new stretch of road is needed because congestion around the Brynglas tunnels in Newport is harming the economy.
Opponents have raised concerns about the impact of the road on the environmentally sensitive Gwent Levels, where the motorway would be built.