Starbucks is fighting an expanded effort to unionize its stores, even as a union vote proceeds at three of the coffee-chain's locations in Buffalo, New York.

Union organizers from three additional Buffalo-area stores appeared before the National Labor Relations Board on Thursday, asking to hold union votes at each of their stores. The workers say they want more input on pay and store operations and they're seeking representation by Workers United, an affiliate of the Service Employees International Union.

Starbucks' attorney at the hearing reiterated the company's request to conduct one vote with all 20 stores in the Buffalo area. The labor board hearing is expected to last for several days.

In late October, the labor board in the Buffalo region approved union votes at three separate Buffalo-area stores. Starbucks has appealed that ruling to the full labor board in Washington, but voting began last month despite that appeal.

The labor board could count those votes as early as Dec. 9. Starbucks has said around 111 employees are eligible to vote at those three stores.

Starbucks has never had unionized workers at its U.S. stores in its 50-year history. The Seattle-based company says its 8,000 company-owned U.S. stores function best when it has flexibility and can work directly with employees.

Starbucks attorney Alan Model noted Thursday that 45.5% of baristas and shift supervisors in the Buffalo area worked at more than one store in the company's 2021 fiscal year, which ended Oct. 3. That helps the company meet shifting customer demand at its locations, Model said.

"It's by design, not happenstance, that you can walk into any store and enjoy the same food and beverage in any store, and its partners can work at any store at any time," Model told a hearing officer from the labor board.

But Ian Hayes, an attorney for Workers United, said the labor board has already determined that individual store union elections are appropriate. Hayes says store managers handle operations in any given store.

"Labor relations takes place at the store level," he said. Hayes also said it's uncommon for baristas to work at different stores.

The outcome of the union election at the first three Buffalo-area stores is still uncertain.

If the National Labor Relations Board denies Starbucks' request for a review of the regional decision, the ballots will be counted on Dec. 9. If the full board decides to review the decision, the ballots will be impounded until the board decides whether to keep the regional decision in place.

In the meantime, the unionization effort is spreading. On Nov. 18, workers at a Starbucks store in Mesa, Arizona, filed paperwork with the labor relations board asking for their own union election.