With a mostly nonunion work force that has voted against labor representation for years, Delta is unique among major airlines.

For years now, the Atlanta-based carrier has been able to fend off labor organizing efforts by investing in a sophisticated campaign: Delta is an attractive place to work, with decent pay and more than a billion dollars in profit sharing bonuses paid out to workers each year. Why risk screwing that up?

But nationally, pro-union public sentiment is growing louder. A new Gallup poll puts union support at a near 50-year high, with support strongest among young people. Statistics show more Americans participated in work stoppages in 2018 than at any time since 1986.

Could the longtime anti-union stronghold finally be vulnerable? Union supporters say it will be an uphill battle, especially in the hostile political environment of the South.

Still, both sides seemed taken aback earlier this year when an anti-union flyer distributed by Delta management went viral. In it, Delta suggested workers would be better off spending the $700 a year they would pay in union dues on video games.

Critics admonished CEO Ed Bastian and said the company, which has been crafting a progressive image on a host of other issues, seemed tone-deaf. The high-profile backlash was unlike any reaction to past union fights against the airline.

Delta's chief marketing and communications officer Tim Mapes said that the poster "was a misstep. What we do is we respect people's right to make a choice" on unionization, and "that didn't come through."

Lynn Rhinehart, former general counsel of the AFL-CIO, said the reaction reflected the changing political climate.

"[The poster] was ridiculing the idea of having a union and what a union can do for working people," Rhinehart said.

Less than 20% of the airline's workforce is union-represented. The company's position is that its flight attendants and ground workers don't need a union because a "direct relationship" between management and workers is the "cornerstone of our unique culture."

Phil LaPorte, a labor arbitrator and professor emeritus from Georgia State University, said, "I think you have some workers who resist unionization as part of their heritage, saying I am independent, I can do it for myself. I don't need anyone speaking for me."

That view is echoed by Candy Bruton, a Delta flight attendant for 48 years who sits on an employee involvement group that works with management. "Personally I think a union is useless and cumbersome for our company," she said in an interview.

But other workers have raised concerns about unfair treatment and the company's separate class of workers, categorized as "ready reserve," who have limited hours and are paid less.

Flight attendant Spencer Hayes, who is leading the union's Atlanta campaign to organize flight attendants, said he wants better health care coverage and better rules for how flight attendants are paid when they have to work overtime.

"The company can do whatever they want and you have to take it," Hayes said. "If you don't, you have disciplinary actions, you can lose your job." He said the company has "put in policies to silence our voice."

Delta has long relied on websites, newsletters, mailers and posters to convince employees that it's a bad idea to unionize. The airline also launched apps for its campaign against the International Association of Machinists (IAM) union.

Delta is "very smart in their campaigns." said Kate Bronfenbrenner, director of labor education research at Cornell University's School of Industrial and Labor Relations.

But IAM assistant airline coordinator James Carlson called the video game flyer "the tip of the iceberg." "We've seen that for years and years and years, and you almost become desensitized," Carlson said.