New York (CNN Business) For the first time, Amazon is offering free shipping on all US holiday orders in an effort to add new Prime members and juice the season's sales numbers.

Last year, Amazon shoppers without Prime memberships had to spend at least $25 to earn free shipping, but Amazon is waiving the purchase minimum starting Monday to give "customers even more convenient and faster delivery options," the company announced.

The National Retail Foundation forecasts holiday retail sales will climb by up to 4.8% compared to a year ago.

Amazon's plan could overshadow holiday strategies from top competitors like Target, which offers free two-day shipping on all orders from November 1 to December 22.

The promotion, available only in the United States, will make hundreds of millions of items eligible for free shipping, Amazon said. By comparison, Walmart, one of Amazon's fiercest competitors, sells around 75 million products online.

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