American Airlines Chief Executive Robert Isom flatly rejected a merger with United Airlines as anti-competitive Thursday, pledged to defend American's Chicago hub and signaled that partnerships — including potentially deeper ties with Alaska Airlines — offer a safer path for growth.

He spoke amid renewed industry ‌consolidation speculation after United CEO Scott Kirby raised the prospect earlier this year of a ​tie-up with American to the Trump administration and as U.S. airlines face tighter limits at congested hubs.

Speaking on the company's first-quarter earnings call, Isom said federal ⁠action to ease congestion at Chicago O'Hare airport would allow American to rebuild its ​schedule to about 500 daily departures.

The U.S. Federal Aviation Administration last week capped flights at O'Hare for ⁠the summer after airlines scheduled more flying than the airport could handle, forcing carriers to scale back plans.

Without those steps, O'Hare "would have likely been in a delay program for the very first flight of the day," Isom said.

Isom said American has no intention of backing down in Chicago, where it competes ​head-to-head with United.

"No ‌one's going to kick us out of Chicago," Isom said, adding the two carriers would be "roommates for a long, long time."

He rejected the ‌idea of a tie-up with United, calling such a deal anti-competitive and bad for customers.

"We're going to be roommates, and we're not getting married," he said.

Isom said American remains open to ⁠opportunities if assets become available but has nothing ‌under consideration now.

Where American does see room to move is in partnerships.

Reuters reported on Wednesday that American and Alaska are in ⁠early-stage talks ⁠to deepen their relationship, potentially by bringing Alaska into American's transatlantic and transpacific joint business arrangements, according to two people familiar with the ‌matter.

That plan has already drawn a warning from American's pilot union, which said it would "vigorously defend" contract protections tied to code-sharing.

"Pursuing a plan to have more of our flying done by another airline is not ‌a path ​to making American Airlines a ‌globally competitive airline," the union said on Thursday.

Isom said any expansion would stay within those labor agreement limits.

American and Alaska already have a partnership built around codesharing, reciprocal loyalty benefits ​and West Coast connectivity into international routes, under what they have described as a "West Coast International Alliance."

Isom said American sees room to deepen ties between the two sides.