Ocado bosses are asking the quartet to reprice parts of the job while the four sweat over the biggest warehouse job this year at the site in Dordon, North Warwickshire.
Vinci, Simons ,Bowmer & Kirkland and Buckingham Group Contracting are battling it out to build the “Customer Fulfilment Centre” on the 35-acre site on the Birch Coppice Business Park.
A winner was due to be announced early this month ahead of construction starting in January with completion set for September 2012.
But Ocado bosses have gone back to the bidders to ask them to fine tune parts of the project which has shunted the process back by a fortnight.
One bidder told the Enquirer: “We are all in the client’s hands now and everyone is on tenterhooks.”
Consulting engineer Waldeck has been appointed by Ocado to carry out civil and structural engineering work at the centre.
Director Matt Tyers said: “This will be a high-tech, cutting edge facility capable of delivering between 180,000 and 200,000 orders a week.
“One of the logistical challenges we face is co-ordinating the external building works with the construction of the internal, highly sophisticated automated system and we’re liaising closely with Ocado’s in-house project management team to ensure everything goes to plan.”