The 2012 opening of the National September 11 Memorial & Museum at the World Trade Center could be delayed because the museum and the Port Authority of New York and New Jersey are arguing over funds.
A spokesperson for The Port Authority, which is building the museum, said it is owed $156 million for construction.
A source told The Associated Press that the authority has slowed construction of the museum, which sits between two voids on a memorial site where the Twin Towers once stood.
But the museum says it is the other way around: the Port Authority owes it $100 million because of delays to the project.
Both sides say they are working together to reach a settlement and that an arbitrator could be brought in. The dispute was first reported by The Wall Street Journal.
Mayor Bloomberg said at a press conference on Monday that he was somewhat optimistic about the impasse being broken.
"I think we'll work things out," he said. "I hope so."
The mayor is the chairman of a foundation that oversees the museum. The total budget for the 8-acre memorial and museum is about $700 million.