Thousands of Amazon.com workers will walk off the job on Thursday at 6 a.m. ET, in the crucial final days before Christmas, after union officials said the retailer failed to come to the bargaining table.

The International Brotherhood of Teamsters said unionized workers at facilities in New York City; Skokie, Illinois; Atlanta; San Francisco; and southern California will join the picket line to seek contracts guaranteeing better wages and work conditions.

The Teamsters union has said it represents about 10,000 workers at 10 of the company's U.S. facilities, representing about 1% of Amazon's hourly workforce.

The strike could disrupt Amazon's operations as it races to fulfill orders during its busiest season of the year. In the New York City area, however, the company has multiple warehouses, as well as smaller delivery depots for fast same-day delivery.

Amazon did not immediately respond to a Reuters request for comment.

The union had given Amazon a deadline of Sunday to begin negotiations, and workers voted recently to authorize a possible strike.

Teamsters local unions are also putting up primary picket lines at hundreds of Amazon Fulfillment Centers nationwide, the union said in a statement on Wednesday.