The final decision on building a £1.4bn M4 relief road in south Wales may be made by the next first minister, Carwyn Jones has admitted.
Wales’ current leader said the Welsh Government had received the 580-page report from the planning inspector after a 13-month public inquiry.
Mr Jones had previously said he would make the decision but he is due to step down in December.
“The decision cannot be rushed,” Mr Jones told BBC Radio Wales.
The Welsh Government wants to build a 14-mile (23km) six-lane motorway south of Newport, between Magor and Castleton.
It says the current M4 is “not fit for purpose” and wants to relieve congestion on the current motorway around the Brynglas Tunnels – a bottleneck once described by former Prime Minister David Cameron as a “foot on the windpipe of the Welsh economy”.
Conservationists say the new M4 across “Wales’ own Amazon rainforest” of the Gwent Levels would be a “direct attack on nature”.
Building a M4 relief road – a scheme first proposed in 1991 – was an election pledge by Mr Jones and would be Wales’ biggest infrastructure project since devolution.
AMs are set to vote on the project in December but Mr Jones admitted: “It’s not absolutely guaranteed I will able to take the decision, although that is still the intention.
“It’s the sort of decision people will be unhappy with whatever the decision and might look to challenge it in court so the proper process has to be followed.”
Finance minister Mark Drakeford is favourite to succeed Mr Jones as Labour leader and first minister and is considered to be more sceptical of building the relief road.
Mr Drakeford’s leadership rivals, health minister Vaughan Gething and Eluned Morgan, are said to be more open to the new route.