Bruntwood acquired the 120,000 sq ft City House building, situated above the station, in summer 2010 and wants to covert it into Grade A office accommodation.
Craig Burrow, director of Bruntwood's Leeds office, told Insider: "It is likely that we will require a pre-let to start development.
"If the situation doesn't improve we are going to find it difficult to secure that pre-let we need."
Burrow said Bruntwood was talking to both Leeds City Council and Network Rail about improving the station.
"We are all coming at it with different angles but with the same ambition," he added.
Network Rail's proposals include a new south entrance, concourse and 350 extra parking spaces. Burrow said the key benefits included a raised main concourse roof, an extra floor of retail outlets and improvements to the entrance on New Station Street.
"We have been trying to align our aspirations with Network Rail with regards to improvements at that end of the station," added Burrow.
A survey by Leeds Chamber of Commerce last year showed that 63 per cent of businesses do not believe that the rail station acts as a good gateway into the city.