CNN Business  — 

A shortage of airline pilots is leading pilots at America’s largest carriers to push for better pay and benefits.

The union representing United Airlines (UAL) pilots said Tuesday its members rejected a tentative contract, voting 94% against the deal. It accused management of delays and said pilots deserve better now that the airline is profitable again.

United said after the vote that it expected the rejection and is “already working with ALPA on a new, industry-leading agreement that we expect to include improved pay rates and other enhancements.”

The announcement comes a day after Delta Air Lines (DAL) pilots voted 99% in favor to authorize a potential future strike. The vote does not mean a strike is imminent, and the timeline does not allow for a work stoppage around Thanksgiving travel.

A pilot shortage fueled by pandemic-era retirements and other issues led many regional airlines — the companies that fly smaller planes under brands like Delta Connection, United Express, and American Eagle — to hike pay significantly. Just last month, the Teamsters announced regional pilots with Republic Airways would see raises between 54% and 94%l

Many pilot careers begin at regional airlines before they move to the mainline carriers, and pay was dramatically lower than at the larger airlines. But the raises and premium pay — such as for training other pilots — means some regional pilots will be able to earn more than pilots at the major airlines.

“There are cases where their instructor pilots are getting paid more than an international widebody captain at American,” said Dennis Tajer, the spokesman for the pilots union at American Airlines and who is also a 737 captain.

American’s pilots may soon consider a tentative agreement between their union — the Allied Pilots Association — and the airline, Tajer said. Analysts at the investment bank Barclays predicted in a report last week that “the new tentative agreement at American likely stands a difficult, if not severely challenged, path to approval.”

The Southwest Airlines Pilots Association recently told its members that negotiations have drawn another $1.2 billion in value from the airline’s previous tentative agreement.

Simultaneous negotiations at all four of the largest airlines are taking place now as the pandemic put negotiations at multiple carriers on hold. It means airline executives are closely watching each other. Agreements also often include provisions that allow for raises if other airlines sign for a higher pay rate.

The situation “is creating a bit of a complication for management, which I think for pilots is a good thing,” Jalmer Johnson, the pay consultant working for the Southwest union, said in a union podcast.

“When one pilot group gets an agreement particularly on major economic issues … it really does set a floor for the remaining groups that are in bargaining to improve upon,” Johnson said. “Those groups are not going to accept something less than has already been established.”

Southwest did not immediately respond to a request for comment on the negotiations.

The votes by United and Delta pilots are not the only way airline contract negotiations have spilled into public view. Delta pilots have held a series of so-called informational picketing events at airports around the country where they sought to raise awareness of their working conditions. Other work groups, including Southwest flight attendants, have done the same.

Delta said despite the strike vote, the airline and pilots “have made significant progress in our negotiations and have only a few contract sections left to resolve.”

“We are confident that the parties will reach an agreement that is fair and equitable, as we always have in past negotiations,” the airline said in a statement to CNN.

Another raise influencing negotiations is Alaska Airlines’ new pilot contract, announced in October, with pay boosts of up to 23% in some bands.

Tajer, with APA, said the Alaska contract “broke through the sound barrier” as negotiations continued at other carriers.

“You have management teams that are actually looking more closely at each other than they are looking at their actual labor groups,” Tajer, with American, said. “All these management teams are worried they’re going to be left as an outlier paying too much.”

- CNN’s Pete Muntean contributed to this report.