Union members voted by a margin of 85% to authorize a strike in response to what it said was the company’s refusal to present a fair contract offer.

More than 18,000 Costco workers will be walking picket lines in less than two weeks if a labor dispute over wages and benefits is not resolved, according to the Teamsters union. Members voted by an 85% margin to authorize a strike when their current contract expires on Jan. 31, the union announced on Sunday.

Teamsters said its members voted in favor of a strike as they entered a final round of talks to reach a new contract ahead of a Jan. 31 deadline.