REI could be heading into its busiest stretch of the year facing a boycott.

Unionized employees will vote next week on whether they should ask customers not to shop at the outdoor retailer during its anniversary sale in May. A vote in favor of the boycott would mark a major escalation in the workers’ yearslong battle for a first union contract.

“I do believe there will be some big support for this, and unfortunately so,” said Anni Saludo, an employee of 15 years at REI’s Durham, North Carolina, location. “It’s not an easy ask, but it is the only avenue I feel that we have to get them to listen to us.”

Workers have organized 11 of REI’s roughly 190 stores over the past four years in a push for higher wages and a voice on the job. REI, which bills itself as a progressive, member-owned cooperative, still hasn’t agreed to a collective bargaining agreement for any of those stores.

An REI spokesperson called the upcoming boycott vote “disappointing,” and said the retailer was “committed to reaching an agreement that supports employees and the co-op’s long-term health.”