Starbucks Corp. drew sharp criticism from investors on Wednesday as a group including major public pension funds pressed shareholders to vote against reelecting two key directors. The coalition cited the company’s ongoing struggles with unionized workers as the main reason for the challenge ahead of the March 25 annual meeting.

The investors’ letter singles out Jorgen Vig Knudstorp, the lead independent director, and Beth Ford, chair of the board’s Nominating and Corporate Governance Committee. They argue the board has failed to build a workable relationship with Starbucks Workers United, the union representing thousands of baristas.

More than 3,800 baristas walked off the job late last year in the longest strike in Starbucks history. Union members demanded better staffing, reliable schedules and higher wages after months of stalled contract negotiations.

New CEO Brian Niccol, who took over last year, faces this labor battle as a critical test while trying to boost slumping sales. The investors warned that unresolved tensions with workers could derail those efforts. “We are concerned that, without a constructive relationship between Starbucks and its unionized workforce, sustaining the turnaround may prove difficult,” the group wrote.

Signatories include New York State Comptroller Thomas DiNapoli, New York City Comptroller Mark Levine, Trillium ESG Global Equity Mutual Fund, SOC Investment Group, Merseyside Pension Fund and the Shareholder Association for Research and Education.

Starbucks pushed back in a statement. “We offer the best job in retail with hourly partners earning an average of $30 an hour and world-class benefits… all for those who only work 20 hours a week on average,” the company said.

This marks the second time in recent months the group has targeted the board. Back in January, they sent a letter to Knudstorp and Ford protesting the board’s decision to disband its Environmental, Partner, and Community Impact Committee with no public explanation.

Starbucks officials said Wednesday that the committee’s duties have been spread across other board committees. The full board now holds primary oversight of labor matters, they added.

The labor dispute has dragged on for years, with Starbucks and the union trading accusations over bargaining tactics. Union leaders have accused the company of stalling fair contract talks, while Starbucks insists it values its workers and offers competitive pay and perks.

Shareholder votes at the annual meeting could signal broader discontent with the board’s strategy. Niccol has prioritized store improvements and menu changes to win back customers, but labor issues continue to grab headlines and test investor patience.

Analysts watching the situation say a breakthrough with the union could ease pressure on leadership. For now, the investor coalition’s move puts Knudstorp and Ford squarely in the spotlight.