Starbucks workers are striking in a dozen cities, according to the union representing more than 10,000 baristas. The five-day strike began on Dec. 20, amid the height of holiday-shopping season.

Starbucks workers are striking in response to an “insulting economic package with no immediate wage increases,” according to Starbucks Workers United.

The strike started in Los Angeles, Chicago, and Seattle, and has added New York, Pittsburgh, and St. Louis—a dozen U.S. cities in total. Walkouts are expected to “continue surging through Christmas Eve,” according to a statement from the union, which represents employees at more than 500 of Starbucks’ 10,000-plus stores in the U.S.

The cities where Starbucks workers are currently striking include:

• Boston
• Dallas
• Fort Worth
• Portland
• Chicago
• Columbus, Ohio
• Denver
• Los Angeles
• New York City
• Pittsburgh
• Seattle
• St. Louis, Mo.

Ed Gainey, the mayor of Pittsburgh, announced his solidarity with the Starbucks workers, declaring on X that his city is a union town.

“When a company refuses to bargain in good faith, we show up in solidarity with the workers who deserve a fair contract,” Gainey wrote. “Now it’s time for Starbucks to fulfill their promises.”

Starbucks didn’t immediately respond to a request for comment from Fortune about the strike.

Picket line is strong at 16th & Walnut Philly Starbucks, come help us shut this store down! pic.twitter.com/noIZSmRd8q

— Philly Workers United (@PJBWU) December 23, 2024

Since December 2021, union workers have been fighting for better pay, schedule, and hours. And although Starbucks and the labor group resumed bargaining earlier this year, the union said the company has “yet to bring a comprehensive economic package to the bargaining table.” The union also alleges Starbucks has engaged in unfair labor practices that remain unresolved.

“The holiday season should be magical at Starbucks,” Arloa Fluhr, who has worked at Starbucks on-and-off for 18 years, said in a statement. “But for too many of us, there’s a darker side to the peppermint mochas and gingerbread lattes.” 

The union and Starbucks have yet to agree on issues related to wages as well as scheduling and staffing. Fluhr said she knows “what it’s like to panic because my hours were slashed” and can’t pay for her bills.

However, Starbucks said in a statement on Dec. 20 the demands made by union workers are “not sustainable.” Workers United proposals call for an immediate increase in minimum wage of hourly partners by 64%, and by 77% over the life of a three-year contract, according to Starbucks.

“These proposals are not sustainable, especially when the investments we continually make to our total benefits package are the hallmarks of what differentiates us as an employer,” according to Starbucks.

Another Starbucks barista who’s worked with the company for five years and serves as a bargaining delegate said the strike is a “last resort.”

“Nobody wants to strike,” Fatemeh Alhadjaboodi said in a statement. “But Starbucks has broken its promise to thousands of baristas and left us with no choice.”

The reveal of new Starbucks CEO Brian Niccol’s pay package also ruffled feathers with the union. In his first year as chief executive, Niccol could make more than $100 million and didn’t have to move from his California home to Seattle, where the coffee giant is based. That major payday feels like a slap in the face to frontline Starbucks workers.

“In a year when Starbucks invested so many millions in top executive talent, it has failed to present the baristas who make its company run with a viable economic proposal and resolve the pending unfair labor practices,” Alhadjaboodi said.

Bernie Sanders, the independent senator and one-time presidential candidate from Vermont, has also voiced his support for the union strike.

“This year, Starbucks signed a $113 million contract to hire 1 CEO. In 3 years, it has failed to sign a fair contract with nearly 12,000 of its union workers,” Sanders wrote in a post on X on Saturday. “This is what corporate greed is all about.”