The Wall Street rating agency that alone rates Chicago bonds as junk on Thursday threw cold water on Mayor Rahm Emanuel’s $8.5 billion O’Hare Airport expansion project.

Moody’s Investors branded the project that Emanuel calls a “game-changer” for Chicago as “credit negative” because it will “increase leverage and airline costs above those of airport peers, weakening O’Hare’s competitive position and airlines’ profitability.”

O’Hare has $7 billion in outstanding general airport revenue and passenger facility charge debt even before the new round of borrowing for the expansion.

If, as expected, the city borrows against future landing fees, terminal rents and concession revenues to bankroll the entire project, O’Hare’s debt load will rise to $14.5 billion by 2022.

That’s “well above the increase” at other major airports, Moody’s said.

“Airline costs most acutely pose risk to connecting traffic, which does not need access to the local Chicago market and can be served by another connecting hub airport,” Moody’s wrote.

“Although airlines can pass increases to passengers, we think cost increases that are significantly higher than the increases of rival airports will diminish profitability and increases the risk of losing connecting services in the future.”

The “credit negative” label is certain to exacerbate Emanuel’s running feud with Moody’s.

The mayor was so incensed by Moody’s junk bond rating he demanded that Moody’s stop rating Chicago bonds.

Although O’Hare already has a mountain of debt, Chief Financial Officer Carole Brown has assured aldermen that the massive expansion plan poses no credit risk either to the airport or the city.

For three weeks, American Airlines was alone among airlines in opposition to the expansion because of the five additional gates awarded to hometown United Airlines.

But American got on board after Emanuel made a hazy promise to speed construction of three additional gates used by all carriers that favor American because they’re located at the end of an American concourse.