A coalition of major investment groups is urging Starbucks shareholders to vote against re-electing two board members at the company's annual meeting on March 25, citing concerns over the coffee chain's handling of union negotiations.

The SOC Investment Group, Trillium Asset Management, Merseyside Pension Fund, the Shareholder Association for Research and Education, and comptrollers from New York state and New York City sent a letter to shareholders calling for votes against board members Jørgen Vig Knudstorp and Beth Ford.

The investor coalition argues that Knudstorp and Ford have contributed to stalling Starbucks' ongoing labor dispute with workers seeking union representation. The coffee company has been engaged in a prolonged battle with employees attempting to organize at stores across the United States.

The shareholder action represents mounting pressure on Starbucks' leadership over labor relations as union organizing efforts continue at locations nationwide. The company has faced criticism from labor advocates and some investors over its response to unionization attempts.

Starbucks has not immediately responded to the shareholder letter. The annual meeting will determine whether the targeted board members retain their positions amid the ongoing labor negotiations.