A decision over whether West Ham can move into the Olympic Stadium could be delayed, it has been revealed.
The Hammers want to become main tenants at the Stratford site for the start of the 2014/2015 season.
However, the Premier League club reportedly remain at loggerheads with the London Legacy Development Corporation (LLDC) over changes which would need to be made to the stadium such as retractable seating - and crucially who would fund them at a cost of around £160million.
LLDC chief executive Dennis Hone told the Guardian's website: "If we can't come to a conclusion, in the scheme of things if it slips another month or two I would rather get the right solution.
"Yes, the stadium is tricky, but it's tricky because we want to get it right.
"I would hate to bung someone in there and see it fall apart in five years. If it takes a couple of extra months to get there, then so be it."
Other bids are under consideration, including one from nearby football club Leyton Orient, a football business college as well as a group wanting to host a Formula One race at the Olympic Park.
But West Ham are hopeful a conclusion to the bidding process can soon be reached.
A club statement read: "It is now 20 months since West Ham United were initially named as the preferred bidder to occupy the Olympic Stadium post- Games. We are obviously disappointed, that three bids later, a decision has yet to be reached.
"We do however remain fully committed to becoming the catalyst to galvanise the Olympic Park by bringing people, jobs and a robust and sustainable commercial offer that guarantees a return to the taxpayer of the money already invested."
The £486m Olympic Stadium has already been earmarked for 20 athletics meetings, which include the World Championships in 2017, and will also be available for community use, with Newham Council contributing some £40million in a loan towards the redevelopment project.
Hone added: "We have had discussions with all of the bidders. The difficulty is that we are balancing the adaptations we have to make to the stadium against the proposals that have come in and the benefits - financial and otherwise - that those proposals bring.
"If it was a knockout [verdict] it would be an easy decision, but it's not."
The bidding process to take over the Olympic Stadium had to be restarted last year after legal challenges from both Tottenham and Orient to West Ham's proposed tenancy.