The Leader of Thurrock Council is to call on his fellow councillors to back a judicial review challenge over the planned Lower Thames Crossing.
The move comes as Highways England this week launched a public consultation on the proposals, ahead of making an application to the Secretary of State for Transport for a Development Consent Order (DCO).
The scheme would involve the creation of a new motorway connecting Kent, Thurrock and Essex through a tunnel beneath the River Thames. Highways England believes that this will "provide much needed road capacity across the River Thames east of London, and transform journeys through the South East region and beyond".
Cllr Rob Gledhill, Thurrock’s Leader, said: "All councillors remain unanimously opposed to the Lower Thames Crossing, as I have made abundantly clear on many occasions, and that position has not changed.
"Contrary to Highways England's claims that the scheme will enable sustainable local development and strengthen and connect local communities, it will in fact just smash through greenbelt land, damage development opportunities and effectively cut the borough in half.”
Cllr Gledhill added: "There is a clear absence of any real connectivity improvements here, only the threat of a motorway and absolutely nothing that will benefit our residents as has been intimated by Highways England. In fact, this proposal will have a completely unacceptable impact on Thurrock.
"Now we know the full extent of Highways England's plans we will go to any lengths in fighting these abysmal proposals, and I will be calling on all councillors, irrespective of party, to back my motion at full council later this month to go to court for a judicial review."
Cllr Mark Coxshall, portfolio holder for regeneration at Thurrock, said: "The way this consultation has been launched without sufficient prior engagement with the council or information from Highways England is entirely inadequate.
"It is publishing consultation documents which run to thousands of pages, yet has refused to provide any information to us in advance. Now we will finally have sight of the consultation materials, officers will carefully review the detail of what is published to ensure we respond quickly and robustly, and can provide information to support the public in responding.
"But whether you were in favour of this option or not, this final proposal bears little resemblance to what was promised and is of no benefit to our borough."
Cllr Peter Smith, Chair of the Lower Thames Crossing Taskforce, said: "Our cross-party taskforce have already achieved some significant successes, including persuading Highways England to carry out a full health impact assessment, and we will continue to fight these proposals in the best interests of our residents.
"We have also agreed 54 mitigation measures which the scheme must deliver and we will now be testing the proposals against these measures to ensure we get the very best outcomes for Thurrock.”
The consultation material is available at www.lowerthamescrossing.co.uk/haveyoursay. It runs until 20 December 2018.