Updated

American Airlines has criticized a last-minute deal cut by Chicago Mayor Rahm Emanuel to expand O’Hare International Airport, saying it would give competitor United Airlines an unfair business advantage.

Emanuel announced the $8.5 billion expansion O’Hare expansion plan Wednesday, the Chicago Tribune reported.

"What this deal is, basically, is a bulldozing at the midnight hour of a level playing field at O'Hare," Dennis Tajer, a member of the Allied Pilots Association, said. "It's endorsing a monopoly with United, and it's not good for our passengers."

"What this deal is, basically, is a bulldozing at the midnight hour of a level playing field at O'Hare."

— Dennis Tajer, Allied Pilots Association

American reportedly accounts for 37 percent of O’Hare’s traffic, but Emmanuel affirmed that the city would carry on with the expansion, regardless of American’s decision.

At a news conference, Emanuel defended the deal as allowing competitors to “grow and keep all the others honest when it comes to pricing,” and that consumers will gain “by that healthy competition that did not exist before.”

The expansion, if approved, would significantly modernize the airport’s existing terminals, and build new ones to accommodate larger planes for international flights.

A vote by the Chicago alderman on the eight-year plan could come as early as next week. The vote would approve a rise in aviation fees in order to finance the project.