Just weeks before the Olympics site selection committee is set to arrive in New York to judge the city’s plans for the 2012 Games, the New York Jets and a state entity announced that they had hit a wall over the price of development rights for a stadium that the Bloomberg administration says is vital to New York’s Olympics bid.

The Jets and the Metropolitan Transportation Authority are haggling over just how much the lease rights to build a stadium above the MTA’s rail yards along the Hudson River should cost.

The president of the Jets, Jay Cross, told reporters yesterday that the team figured the lease was worth about $35 million and the team offered the MTA $100 million. The MTA does the math differently. It puts the value of the entire 560,000-square-foot parcel at $900 million and wants the Jets to pay $300 million for air rights over a portion of the property.

“We have an impasse,” Mr. Cross told reporters at the team’s midtown Manhattan offices yesterday. After months of negotiation, he said, the two sides couldn’t bridge their $200 million difference of opinion.

Rather than draw out the fight, the two sides called in an arbitrator to settle the dispute. As if to underscore the gravity of the project, the two sides chose a referee who not only brokered a peace accord in Northern Ireland but stepped in as chairman of Disney when corporate titans locked horns: a former Senate majority leader, George Mitchell. The Democrat from Maine has become the poster boy of mediation, tackling third-rail issues that no one else is willing to touch. His reputation for finding common ground is such that both the Jets and the MTA have said they are willing to accept whatever price he comes up with.

“If his view is much closer to the MTA’s, then that’s what we’ll be bound by,” Mr. Cross said.

That’s good news for Mayor Bloomberg, a political consultant, Scott Levenson, said.

“This will get settled because they named a superstar arbitrator,” he said. “The message they are trying to send is not how far apart they are, but, regardless what happens in the next couple of rounds, someone is standing in the wings to fix it. So in that sense this is very good for Mike Bloomberg.”

The mayor, the Jets, and the MTA clearly want to make a deal.

If the stadium project goes forward, the Jets stand to gain as much as $120 million a year in extra revenue. Not only would they come away with a shiny new riverfront home, they would also have luxury boxes to sell, a stadium naming-rights franchise, first-class club seats available for subscription – and may end up hiking ticket prices after the team’s move from New Jersey to Manhattan.

The MTA, which has financial problems of its own, is well aware of what is at stake.

The MTA’s chairman, Peter Kalikow, and Mr. Cross have already met with Mr. Mitchell. The next step is to draw up the rules governing the mediation process. Mr. Mitchell has not done that yet, Jets officials said. The MTA’s board also has yet to approve the agency’s commitment to binding arbitration. Mr. Cross, when asked by reporters, said he hoped that the price of the development rights could be worked out before the Olympic committee arrives for its tour on February 21.

Real-estate experts said that even if this project weren’t politically charged, the two sides would have been expected to come up with appraisals that appear to have come from different worlds. That is commonplace.

“Appraising the property’s fair market value is a complex process,” the president of the Real Estate Board of New York, Steven Spinola, said. “Appraisals differ because of the assumptions that each appraiser utilizes. Often these differences are negotiated between the parties.”

The haggling over air rights is just the latest in a roster of complications that have beset a project in which Mr. Bloomberg has invested tremendous personal political capital. He envisions a broad, multi-billion-dollar project that would transform the far West Side of Manhattan between 30th and 42nd streets into a new business center in the city, and he has been a tireless advocate for the project.

Mr. Bloomberg has made the case that the mixed-use development will create thousands of jobs, through convention space, office space, and stores, as well as housing and parkland. More pressingly, he portrays it as crucial to the city’s effort to be named host of the 2012 Summer Olympics. He paints the project as a boon for the city because the Jets have said they will invest at least $800 million in the stadium and cover cost overruns. In return, the city and the state would finance construction of a platform that would cover the rail yards and provide the foundation for the New York Sports & Convention Center, as well as its retractable roof.

“The plans for the West Side are symbolic of Bloomberg’s belief that you have to grow the economy,” Mr. Levenson said. “A failure of the stadium is a failure of that message, and that would obviously cause perception problems for the mayor. He is trying to replicate what Battery Park was a generation ago, and that’s important for him.”

Hours after the Jets and the state announced their decision to turn to arbitration, the Democratic front-runner determined to unseat the mayor in November, Fernando Ferrer, sought to rekindle the debate.

Last month, Mr. Ferrer urged the mayor to have a referendum on the stadium added to the November ballot. The Bloomberg administration rebuffed the request, noting that the International Olympic Committee’s decision on the 2012 site is due four months before Election Day.

Yesterday, the former Bronx borough president demanded an end to the backroom deals that he said have characterized the development project. He called on Mr. Bloomberg to open up a bidding process for the lease rights.

“Let’s guarantee the public gets a fair price for the sale of this land,” Mr. Ferrer said in a written statement to reporters yesterday. “It’s becoming clearer every day that Mayor Bloomberg is using the MTA to broker a stadium deal for the billionaire owner of the Jets without any public debate. Since the appraisals have been done in secret, New Yorkers don’t know the true value of this land.” The football team is owned by Robert Wood Johnson III.

Assemblyman Richard Brodsky, a Democrat who represents Westchester, agrees. He is holding a hearing tomorrow in Manhattan to question the MTA chairman, Mr. Kalikow, about the appraisal.

“If the development rights are worth $900 million, why should the MTA take a penny less than that?” Mr. Brodsky told The New York Sun in an interview. “The big question is should the assets of the MTA be available for projects – good or bad – outside the MTA, or should they be available to protect the people who ride the subways? That’s what we’ll be asking.”