(Reuters) - Teamsters said on Sunday its members at U.S. retailer Costco Wholesale ( COST ) 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.

The union, which represents more than 18,000 workers at Costco, said 85% of its members voted to authorize a strike.

"The vote is a direct result of the company's continued failure to bargain constructively," the union said in a post on X, adding that the master agreement between the two parties expires on Jan. 31.

Costco did not immediately respond to a Reuters' request for comment outside regular business hours.

The final week of negotiations begins on Jan. 20, the union said in another X post.