Cheshire West & Chester Council has called for further technical audits of the two locations vying to become home to the city's new theatre.
Councillors will discuss the type and method for gathering information needed to choose between the preferred Odeon and Little Roodee locations at next month's meeting of the council executive on 9 March.
Cllr Richard Short, executive member for culture and recreation, said: "It had been hoped that we would be able to make a decision on the basis of reports available to the March meeting.
"However, it is now clear that issues with both sites will require further risk-mitigation information to allow this to take place."
A statement from the council said "uncertainties, particularly involving archaeological, conservation and access issues, make it impossible to predict when the final reports will be available."
Short added: "Despite this we are still working to a 2015 deadline for a new iconic Chester theatre."
A full archaeological survey of the current Little Roodee car park is necessary after a desktop appraisal failed to provide the complete information required to assess its potential archaeological importance.
In addition, further work is needed on traffic flow – particularly the effect of increased traffic movement on the junction between Castle Drive and Grosvenor Bridge – and accessibility issues involved in the possible development of the Riverside land.
With regard to the privately-owned Odeon site, similar comprehensive reports are awaited on traffic, access and listed building aspects of the proposal.
In a report to the executive, from director of regeneration and culture, Charlie Seward, members will be asked to note that £38m has been set aside in the authority's capital programme for the provision of the theatre and to authorise expenditure on further feasibility works necessary.
The executive will also be asked to considering options for the procurement process for the theatres design, which could, if agreed, be the subject of a national competition for architects.