At a news conference Friday, Daley said the government needs to move as quickly as possible on the expansion.
Federal officials earlier this week said the secretary of transportation might have to impose flight limits to ease congestion at O'Hare. All but the two largest airlines have refused requests to cut flights.
The airlines and the Federal Aviation Administration have been holding informal talks to try to curb chronic delays at O'Hare. Daley says the government needs to stop studying the airport expansion plan and give it the go-ahead.