After a high-stakes powwow in Washington between Daley and airline executives, which U.S. Transportation Secretary Ray LaHood brokered, the parties said there was no agreement on what airlines should pay for the ongoing expansion at the major air-travel hub. They did, however, say they intended to talk again at some point.
Daley's trip to the nation's capital to meet with CEOs from American and United - the largest airlines out of O'Hare - underscores how much he is scrambling in his final days in office to boost capacity at O'Hare to guarantee its long-term viability.
"He has put his heart and soul into airports since the day he was elected, and he sees this expansion as one of his biggest achievements," said Joseph Schwieterman, a Chicago-based transportation expert. "And he may think it's unfair to hand all this over, unresolved, to an incoming mayor."
But United and American filed a lawsuit last month that could dash Daley's hopes of resolving the issue before he leaves office in May. The suit wants the city from issuing bonds to finance the expansion, charging that Chicago is violating a lease agreement that gives airlines authority to approve expenditures for capital projects.
In a joint statement following Wednesday's meeting, the two airlines indicated they and the city remain far apart, so they were "unable to reach an agreement that would permit us to suspend our litigation."
Unless a deal is forged and the lawsuit within, litigation could drag out for months, even years.
O'Hare is one of the country's busiest and most congested airports. And city officials argue that finishing a second phase of expansion, which would include a new runway and terminal, will help reduce delays in Chicago and throughout the U.S. air-transport system.
The first phase of the project culminated with the completion of a new runway and a control tower in 2008. A plane carrying Daley and other VIPs was the first to officially touch down on the stark white concrete as part of runway-opening ceremonies.
Airlines, however, have balked at footing most of the bill for more upgrades, saying they will benefit little. Daley counters the airlines are being short-sighted, and last week, he suggested that they might be biding their time until he leaves office.
Daley is closely associated with dozens of ambitious, mega-sized projects, including the development of a park that hugs Michigan Avenue, called Millennium Park. But Daley has clearly viewed O'Hare expansion a signature project from his 22 years as mayor, and he has talked about it as being critical to Chicago's economic future.
Still, most mayoral candidates vying to replace him have also been vocal supporters, including Rahm Emanuel, President Barack Obama's former chief of staff.
In his Wednesday statement, Daley merely alluded to what he called a "candid conversation" with airline executives. He said he looked "forward to a solution that will benefit everyone involved."
A lack of money hasn't been the only obstacle.
The small suburb of Bensenville engaged in a David-and-Goliath legal battle for years to stop Chicago from bulldozing more than 500 homes in the path of one runway project. It finally agreed to give up the fight two years ago in exchange for a one-off, multimillion payment.
There has also been litigation over cemeteries on land that would become part of an expanded O'Hare. Last month, city officials said they hope to resume unearthing bodies soon at one the cemetery, despite the continued opposition of some who have relatives buried there.