(NEW YORK) — Thousands of Starbucks employees nationwide are set to walk off the job on Thursday in the largest work stoppage in the five-decade history of the company, the union representing the workers said in a statement to ABC News.

Employees at hundreds of unionized stores will call on Starbucks to bargain labor contracts that would set conditions at those workplaces, such as pay, benefits and staffing levels, Starbucks Workers United said.

Since 2021, the union has organized more than 360 stores employing roughly 9,000 workers. But the union and Starbucks have yet to reach an agreement on a labor contract at any of the stores.

The strike will coincide with “Red Cup Day,” an annual promotion that brings many customers to the company’s stores for a free holiday-themed reusable cup.

Workers at stores in 30 cities, including New York and Philadelphia, walked off the job a day early on Wednesday and will remain on strike through Thursday, the union said.

Moe Mills, a Starbucks employee who works at a store in St. Louis, told ABC News that they plan to participate in the strike because the company has refused to bargain with the union over staffing decisions tied to the sales uptick associated with promotional events like “Red Cup Day.”

The store where Mills works typically brings in about $8,000 in sales each day but promotional events add at least an additional $3,000 in revenue, which amounts to a nearly 40% increase in business, Mills said.

Starbucks, however, leaves staffing levels unchanged on promotional days, leading to overworked employees and unsatisfied customers, Mills added.

“It’s degrading and embarrassing to work in stores that are so short staffed on promotional days that we give customers poor service,” Mills said. “When customers spend $10 or $12 on a drink, they shouldn’t have to wait 45 minutes or get a lukewarm drink when it should be hot.”

Mills said their store unionized in August 2022 but Starbucks representatives have only attended one bargaining session, which they walked out of after 15 minutes.

“Starbucks is promoting that it’s bargaining in good faith but that’s not what we’re experiencing,” Mills said.

In a statement to ABC News, a Starbucks spokesperson faulted the union for a failure to make progress in contract negotiations, noting that the walkout would involve a fraction of the company’s overall workforce.

“We are aware that Workers United has publicized a day of action at a small subset of our U.S. stores this week. We remain committed to working with all partners, side-by-side, to elevate the everyday, and we hope that Workers United’s priorities will shift to include the shared success of our partners and working to negotiate union contracts for those they represent,” the company spokesperson said.

“Despite escalating rhetoric and recurring rallies demanding contracts, Workers United hasn’t agreed to meet to progress contract bargaining in more than four months,” the spokesperson added.

The company pointed to two union contracts reached with United Steelworkers this summer and progress on a draft contract with the Teamsters as proof of its commitment to settling union agreements.

The single-day strike will draw attention to the labor campaign and direct public pressure at Starbucks, Art Wheaton, a labor professor at the Worker Institute at Cornell University, told ABC News.

Federal labor law requires Starbucks to bargain in good faith with the unionized workers but does not mandate that the company agree to a contract, Wheaton added.

“Starbucks has to continue to bargain but it never has to say, ‘yes,’” Wheaton said. “The workers have 350 stores that they’ve unionized and exactly zero labor agreements.”

“The strike can raise awareness and help boost union morale,” he said. “To get a contract you need solidarity events that get the membership engaged and the community engaged.”

The walkout is set to arrive less than two weeks after Starbucks announced that it would raise the hourly pay of U.S. retail employees by 3% at the outset of next year.

The minimum pay raise falls short of the annual pace of inflation, which stands at 3.2%.

In addition to the pay increase, Starbucks will reduce the minimum number of days an employee must work in order to qualify for paid vacation benefits, the company said.

Alex Yeager, a worker at a Starbucks store in Albany, New York, who belongs to the union, previously told ABC News in a statement that he expects the company to provide the raises to nonunion stores only.

“Once again, Starbucks is responding to our bargaining demands, but they’re implementing them in nonunion stores and denying these new benefits to workers in stores that are unionizing or already voted to join the union,” Yeager said.

A labor board judge ruled in September that Starbucks had illegally provided previous pay increases and benefits to nonunion employees without offering them to unionized workers. Bloomberg Law first reported on the ruling.

In a statement to ABC News, Starbucks rebuked the union’s allegation that the raises would only be provided to workers at non-union stores.

“All union-represented stores will receive annual wage increases consistent with our practice of providing yearly wage increases,” Starbucks said. “Wherever we can quickly and broadly improve partner benefits and perks we have and always will.”

“Starbucks has adhered to long-standing legal obligations, which require the company to differentiate between unionized or organizing partners and partners in all other stores,” the company added.

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