Amazon.com Inc. workers at the company’s sole unionized warehouse in the US joined a broader strike by the International Brotherhood of Teamsters.

The union is aiming to pressure the online retailer by threatening delays in package deliveries during the critical holiday season.

A spokesperson for Amazon said the union claims they represent “thousands of Amazon employees and drivers” when they don’t.

Union organizers have called an end to a five-day strike against Amazon by about 100 Atlanta drivers who joined other workers around the country

The Staten Island Amazon facility, known as JFK8, employs more than 5,000 workers, and about 100 of them joined the picket line early Saturday.

Bundled up and huddled around propane and diesel heaters, the group appeared upbeat and optimistic as strike organizers provided them with hats, jackets, hand warmers, beverages and snacks.

The Teamsters said the strike will begin Thursday at several facilities, including in New York City, Atlanta, California and Illinois.

The International Brotherhood of Teamsters said workers at seven Amazon facilities will begin a strike on Thursday morning.

The Amazon workers who walked off the job at warehouses across the country at peak season are trying to establish a union beachhead against one of the most important — and most anti-union — employers in the world.

A “stressed” driver for Amazon admitted to ditching about 80 packages undelivered in the woods just days before Christmas, Massachusetts police said.

Thousands of workers from Amazon and Starbucks are currently striking this holiday season, as they seek to leverage the increased consumer traffic to demand better working conditions and higher wages.