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.

Thousand of Costco Teamsters across the U.S. are preparing to strike by the end of the month if the company does not present a "fair contract offer," the union says.

At practice pickets in Sumner, workers held red, white and blue signs with the words “Strike Ready! A taste of what’s to come!” and “Just sampling.”

Teamsters said on Sunday its members at U.S. retailer Costco Wholesale voted in favor of a nationwide strike, as they entered a final round of talks to reach a new contract ahead of a Jan. 31 deadline.