So what happens in the industrial action at Starbucks?

A daylong holiday strike against Starbucks ended Tuesday in the largest-ever walkout by the company’s unionized workers, involving walkouts at more than 300 stores in dozens of cities nationwide, the Starbucks Workers United union said.

“The company should be concerned because this is just the beginning,” Michelle Eisen, a Starbucks barista in Buffalo, New York, and a member of the union’s bargaining team, told ABC News.

The union and the company are still without a collective agreement in organized shops. Months of negotiations recently broke down over a disagreement over financial issues, including potential wage increases.

As workers fold up their placards and return to their jobs, a question emerges: What happens next?

Labor experts who spoke to ABC News said the labor unrest could pave the way for a resumption of negotiations and an eventual contract agreement as both sides find grounds to resolve the conflict.

But if a deal proves elusive, workers could escalate their opposition to the company with further strikes or other pressure tactics, the experts said. The company could also pivot toward a more adversarial approach, leaving the bargaining table and cracking down on union organizing, the experts added.

The strike in recent days interrupted a period of relative calm between Starbucks and the union.

Starbucks Workers United and Starbucks announced in February that they would work on a “basic framework” to reach a collective agreement for unionized stores. The union says Starbucks has failed to offer a viable proposal on financial issues, also taking issue with the company’s alleged refusal to resolve federal charges of illegal anti-union conduct.

Workers United told ABC News in a statement that Starbucks had proposed no immediate pay increases for most baristas and a guarantee of only 1.5% pay increases in the coming years.

Meanwhile, Starbucks said in a statement that the union had proposed an immediate 64% increase in the minimum wage for hourly associates, as well as an overall 77% increase over the course of a three-year contract. “This is not sustainable,” a Starbucks spokesperson told ABC News.

Starbucks United disputes those numbers as an unfair characterization of its proposal, the union told ABC News.

“We’ve reached the position in the negotiations where we have to remind Starbucks of who we are,” Eisen said, pointing to public awareness and worker strength demonstrated by the recent strike.

Starbucks did not immediately respond to ABC News’ request for comment.

Sara Kelly, Starbucks’ executive vice president and chief partner officer, downplayed the impact of the strikes in a public letter to employees late Monday.

“The overwhelming majority of Starbucks stores nationwide are open as scheduled and busy with customers enjoying the holidays,” Kelly said, noting the company operates 10,000 stores and employs 200,000 people nationwide.

“The union chose to walk away from negotiations last week,” Kelly said. “We are ready to continue negotiations when the union comes back to the bargaining table.”

The workforce display could prompt a better offer from Starbucks, as the company may recognize the public relations threat from the prospect of more headline-grabbing labor protests, some experts said.

“Starbucks has to constantly worry about bringing a new generation of customers to their product,” Matthew Bodie, a University of Minnesota law professor who focuses on labor issues, told ABC News, pointing to the company’s reputation as a liberal minded employer.

Still, federal labor law gives wide latitude for a company to delay a collective bargaining agreement and lacks the major penalties needed to force a deal, giving Starbucks significant leverage over the next step in the labor dispute, Bodie added.

“The traditional management playbook is fight, fight, fight,” Bodie said. “I see it very much as a decision for Starbucks to make because our system gives so much power and discretion to companies in how they administer collective bargaining.”

If Starbucks chooses to abandon a new proposal, the union could shift toward a more militant strategy similar to the campaign’s previous approach, experts said.

In 2022 and 2023, Starbucks workers at the company staged about 100 strikes a year, Johnnie Kallas, a University of Illinois labor relations professor who tracks strike activity, told ABC News. The recent holiday strike marks the first walkout of 2024 since the union had pivoted to a more cooperative approach amid negotiations, Kallas said.

“If Starbucks doesn’t meaningfully negotiate on economic proposals, you’re going to see an increase in militancy,” Kallas said. “The workers may reach a crossroads.”

Meanwhile, the company could also choose a more adversarial approach, experts said. Negotiations this year have reflected a friendlier public stance from Starbucks. As recently as last year, former Starbucks CEO Howard Schultz said he did not believe unions had any place at the company.

The National Labor Relations Board, or NLRB, the federal agency that enforces labor rules, is expected to become more sympathetic to management under President-elect Donald Trump, experts said. Starbucks could shift toward an increasingly hostile approach, knowing it is unlikely to face much pushback from the NLRB, the experts added.

“If it remains a private negotiation between Starbucks and the union, it can’t go anywhere under Trump,” John Logan, a professor of American labor history at San Francisco State University, told ABC News.

For now, Eisen said, union members plan to catch up on some rest over the holidays and weigh the way forward. Beyond question are the union’s plans to continue organizing new stores, Eisen said.

Workers United organized more than 150 stores by 2024, bringing the total number of unionized stores to about 540.

“You always want your movement to grow,” Eisen said. “The bigger we are, the stronger we are.”