Rossann Williams, who led Starbucks’ largest market with over 18,000 stores for four years, is leaving the company, Starbucks said Friday. 

Williams, a 17-year Starbucks veteran at the center of the company’s response to a unionization push in the U.S. and Canada, will leave Tuesday. She was offered a different position in the company but declined, Starbucks said.

“We have made a difficult, but necessary change to our North America business,” Starbucks said in a letter to employees, “a change that creates new leadership for a new era at Starbucks.”

Williams, along with CEO Howard Schultz, was the subject of complaints filed with the National Labor Relations Board that argued the company had engaged in unfair labor practices. Regional NLRB offices have received 289 petitions for union elections, and 151 stores have unionized, the agency said.

Williams is the second executive who had been close to the union response to leave Starbucks this spring. In April, the company’s top attorney, general counsel Rachel Gonzalez, was removed from her role as Schultz returned as interim CEO.

Schultz has had a strict stance against unionization, saying the unions “shouldn’t lead our people,” and describing the unionizing efforts as a proxy for a larger, generational discontent with business.

Sara Trilling, Starbucks president of Asia Pacific, the company’s fastest-growing market, will take over as the head of North America. She led Starbucks’ store count growth in the region “and digital offerings to meet unprecedented customer demand across the 14 markets in the region,” the company said.