Mayor Martin J. Walsh is demanding IndyCar promoters get their act together, issuing an ultimatum to “finalize” deals with state agencies soon, in a major toughening of his stance on the planned Labor Day road race.

In an emailed letter obtained by the Herald, Walsh’s chief of operations, Patrick Brophy, gave IndyCar just 14 days to reach financial and other agreements with several agencies that control most of the planned course on the waterfront.

“It is expected that your team will finalize agreements with all interested parties within the next two (2) weeks,” Brophy said in an email Friday to Jim Freudenberg, chief commercial officer for the Grand Prix of Boston, local promoters for the race. “Please be advised that the Mayor grows increasingly concerned with the progress (or lack thereof) of those discussions.”

Brophy also asked race promoters to hold off selling tickets to the event until those agreements are signed with other agencies. IndyCar had planned to sell them to the public this month.

Walsh has been the chief cheerleader for the race but has been criticized for signing a deal with IndyCar that could leave taxpayers footing a hefty bill. His shift in tone comes after a series of Herald reports about Grand Prix of Boston’s failure to get approval from Massport, the Massachusetts Convention Center and MassDOT to hold the race on their property.

It’s unclear whether Grand Prix of Boston can get agreements signed in less than two weeks. Sources said race organizers have made more progress recently meeting with state officials, but there are a number of potential problems that could scuttle a deal.

Massport’s CEO told the Herald he would not spend as much as a half-million dollars in public money for road improvements and other changes he said race organizers had requested.

Convention center authority director Fred Peterson told the Herald his agency wasn’t “anywhere close” to reaching agreements to use their property and roads, which are at the center of the race course.

State transportation officials also have not given permits to hold the race on the South Boston Bypass Road.

In his letter to IndyCar, Brophy also said the mayor is concerned about growing complaints from activists in the Seaport District and Fort Point Channel about the race’s impact on their community.

“As you are aware, a predicate to agreements and permit acquisition is the outcome of your discussions with local neighborhood, civic and business associations,” Brophy said. “Mayor Walsh feels strongly that overall community ‘buy-in’ and timely resolution of all financial terms for this proposed event are paramount to his final approval.”

Walsh in fact already signed a deal with Grand Prix of Boston back in May, but aides say the deal can be called off if other agencies don’t sign agreements for use of the course.