Thousands of workers who deliver packages from seven Amazon facilities across in the United States, have on Thursday morning, embarked on a country-wide strike as part of efforts to force the e-commerce giant into a labour agreement, targeting the holiday shopping rush.

According to the International Brotherhood of Teamsters, the union that represents a small portion of 10,000 workers at 10 Amazon facilities, the workers decided to go on strike after Amazon did not act on a December 15 deadline for contract negotiations with drivers and warehouse workers.

“Amazon is pushing its workers closer to the picket line by failing to show them the respect they have earned,” Teamsters General President Sean M. O’Brien said in a statement.

He added that “If your package is delayed during the holidays, you can blame Amazon’s insatiable greed. We gave Amazon a clear deadline to come to the table and do right by our members. They ignored it.”

Amazon said it has no obligation to bargain with the drivers as they are not employees of the company but rather workers of companies contracted by Amazon to deliver packages to customers.

However, Teamsters and the workers insist that Amazon ultimately dictates their working conditions and must negotiate with them. The union is demanding that the retail giant recognise its unionised workers in the U.S. and resolve issues regarding Amazon’s working conditions.

Teamsters said the Thursday strikes are ongoing in Amazon hub in San Francisco and six delivery stations in Southern California, New York City, Atlanta and the Chicago suburb of Skokie, Illinois with the union stating that Amazon workers at the other facilities are “prepared to join” them.

“What you see here are almost entirely outsiders — not Amazon employees or partners — and the suggestion otherwise is just another lie from the Teamsters,” Amazon said in a statement, referring to people picketing outside the delivery hubs.

“The truth is that they were unable to get enough support from our employees and partners and have brought in outsiders to come and harass and intimidate our team,” the company added.