Staff at troubled engineering firm Cleveland Bridge are being warned to prepare for redundancies after a deal failed to materialise.
The Darlington-based firm entered administration in July but several potential buyers came forward.
Production resumed in August, but now administrators say they "must prepare for the prospect that the business will cease to trade" after 20 September.
There are 104 workers on site with 29 on furlough.
A statement from administrators FRP said they had "engaged with interested parties from across the globe" and production began again on 9 August.
There have been lengthy discussions with one "potential purchaser" but "assurances required from the buyer to confirm their ability to proceed have not been received", the statement said.
"Whilst the administrators will keep this dialogue open, they must prepare for the prospect that the business will cease to trade following completion of final production in week commencing 20 September," the statement said.
Martyn Pullin, partner at FRP and joint administrator of Cleveland Bridge, said: "We have worked tirelessly in the hope of finding a buyer who would continue to operate Cleveland Bridge as a going concern, running a thorough and extensive sales process.
"However, with no current viable offers remaining to take the business on, we must now prepare for a property and asset sale.
"Regrettably, production will finally end on site later this month. Our specialist employment team will continue to work closely with the staff, their representatives, unions and the council to support all the workers through what we know has been an extremely challenging time."
Cleveland Bridge was founded in 1877 and has helped build structures all over the world including Wembley Stadium's arch, London's Shard and Dubai International Airport.