Hilary Russ

NEW YORK (Reuters), Employees of a Starbucks Corp (NASDAQ: ) Cafe in Mesa Arizona have indicated they are interested in joining a union. It is part of an increase of labor organizations’ efforts to expand their reach to more locations of the coffee chain.

Six stores of Starbucks in Buffalo, New York, have stated that they plan to join Starbucks Workers United. This affiliate is part of Service Employees International Union.

Three locations offer the opportunity to vote by mail for eligible workers. The ballots are due December 8.

Thursday’s tweet by the union stated that a letter was sent to Starbucks CEO Kevin Johnson concerning Arizona.

The letter stated six store employees who were leading the organizing, that they had formed a union “because it is the best and most meaningful way to help our company partnership” and to ensure their equal power.

Starbucks called its employees partners in a statement. It stated that “We support the right of our partners to have their voice heard and are committed to listening.”

The company stated that their success is based on “the belief that we can build another kind of business by working together as partners.”

Bloomberg first reported on the organizing in Arizona. Workers United had planned to petition the National Labor Relations Board for an election.

Starbucks in Buffalo has fought back against unions by disputing aspects of election results with the NLRB. The company has hired more managers and former CEO Howard Schultz to speak directly with workers, as well as holding meetings to extoll the merits of its wage rises and other benefits.