The workers’ union hopes that adding employees at the Staten Island warehouse to a protest started by delivery drivers will increase pressure on Amazon.

Signaling an escalation in a labor campaign that began at seven Amazon delivery hubs on Thursday, workers at the company’s largest Staten Island warehouse began a protest there at midnight Saturday morning. They were joined by New York’s attorney general, Letitia James, later in the morning.

The Staten Island warehouse, known as JFK8, has more than 5,000 workers, by far the largest group at Amazon who have sought to be represented by the International Brotherhood of Teamsters. That makes it the union’s greatest potential source of leverage as the Teamsters tries to pressure Amazon to bargain with drivers and other workers who have organized.

“Amazon is jeopardizing the holidays for consumers so they can try to make an extra buck,” Connor Spence, president of the local chapter representing workers at JFK8, said in a statement. “Amazon workers are standing up to demand this corporation finally treat them with respect.”

The Staten Island warehouse, known as JFK8, has more than 5,000 workers, by far the largest group at Amazon who have sought to be represented by the International Brotherhood of Teamsters.Dakota Santiago for The New York Times
Some workers at the Staten Island warehouse walked off the job after midnight on Saturday.Dakota Santiago for The New York Times

Unlike the drivers the Teamsters have attempted to unionize at delivery hubs, the Staten Island workers are employed by Amazon directly rather than through contractors. That gives them a somewhat stronger legal foothold for challenging the company.

But union leaders at JFK8 have struggled to sustain the support of workers in the warehouse since they voted to unionize in 2022, and only several dozen workers were participating in the action late Saturday morning. Some said they had been scheduled to work that day and used unpaid time off, while others said they had not been scheduled to work.

That raises questions about how much of an impact they will have on Amazon’s operations during the critical holiday season. Similar questions have accompanied the Teamsters-led walkouts at delivery hubs in New York, Georgia, Illinois and California that began Thursday.

Kelly Nantel, a spokeswoman for Amazon, said the protest had not impacted the Staten Island warehouse.

Sean O’Brien, general president of the International Brotherhood of Teamsters, center, walking with Teamsters on the picket line at an Amazon warehouse in City of Industry, Calif., on Friday.Alex Welsh for The New York Times
Members of the International Brotherhood of Teamsters picketing at an Amazon warehouse at City of Industry on Thursday. One of the chants, “Help us out, drop your route,” was directed at delivery drivers coming in and out of the site.Alex Welsh for The New York Times
Teamsters members speaking to drivers leaving an Amazon warehouse in City of Industry on Thursday.Alex Welsh for The New York Times

The JFK8 workers joined a union called the Amazon Labor Union when they voted to unionize in 2022. The A.L.U. was initially independent, but it struggled to secure gains from Amazon, which challenged the election outcome and has refused to recognize or bargain with the union. (The National Labor Relations Board certified the election, but a federal court paused further action on the case while the company challenged the constitutionality of the board.)

In June, the A.L.U. affiliated with the Teamsters under an agreement that gave the new A.L.U. local the exclusive right within the Teamsters to organize Amazon warehouses in New York City. The agreement also promised that the international union would help the local with organizing, research, communications and legal matters.

At the time, A.L.U. leaders said that the Teamsters told them that the international union had allocated $8 million for organizing efforts at Amazon, and that the Teamsters were also prepared to tap a strike fund of more than $300 million to support the effort.