Jayapal’s bill was introduced on June 11 and will be considered on Wednesday by the Judiciary Committee along with five other bipartisan antitrust reform bills, with votes to advance the measures to the House floor expected this week. There’s no Senate companion for the legislation, and support in that chamber is unclear, clouding its prospects.

While the bill may never become law, it’s the clearest indication yet how lawmakers are gunning to rein in the market power of Amazon, where U.S. shoppers will spend $386 billion this year and which captures 41 cents of every dollar spent online, according to EMarketer Inc. Amazon’s promise of fast delivery helped it become the dominant online retailer in the U.S.

Amazon’s logistics business will be worth as much as $230 billion in 2025, more than Coca Cola Co., according to a research note last year from Bank of America Corp.

“The bipartisan Ending Platform Monopolies Act requires dominant platforms including Amazon to divest lines of business — such as Fulfillment by Amazon — where the platform’s gatekeeper power allows it to favor its own services,” said Jayapal spokesman Chris Evans. “Numerous third-party sellers reported feeling that they had no choice but to pay for Fulfillment by Amazon in order to sell their products,” said Evans, referring to the House Democrats’ investigation and report.

An Amazon spokesman declined to comment.

Jayapal’s legislation shows how some lawmakers want to blunt Amazon’s rapid growth in the logistics industry, which poses a threat to United Parcel Service Inc. and FedEx Corp. Amazon has been reducing its reliance on its longtime partners, including the U.S. Postal Service, in favor of delivering products on its own.

More than half of the products sold on Amazon come from independent merchants who pay Amazon a commission on each sale. Merchants can handle packing and shipping items on their own, but many say they use Amazon’s service and pay Amazon additional fees because that gives their products better placement on the site and boosts their sales, according to the Democrats’ report. Amazon’s third-party seller service revenue, which includes commissions and logistics, exceeded $80 billion in 2020, nearly double the $45 billion in sales from its cloud-computing division Amazon Web Services.

Amazon uses algorithms to determine which products appear most prominently on the site in response to keyword search terms entered by shoppers. Much of the most visible space goes to paid advertisers. Mixed in are products that Amazon believes are preferred by consumers. Exactly how the algorithm works is a well-kept secret. It includes factors like price, the reputation of the merchant and whether Amazon can deliver it to the customer quickly. Merchants have said they use Amazon’s logistics services as a way to get better visibility on the cluttered site.

In a 2019 letter to federal lawmakers, an online merchant accused Amazon of forcing him and other sellers to use the company’s expensive logistics services, which in turn forces them to raise prices for consumers. The letter accused Amazon of “tying” its marketplace and logistics services together, a potential antitrust violation in which a company uses dominance in one market to give itself an advantage in another market where it’s less established.

Sellers said in interviews that delivering products on their own was potentially less expensive than Amazon’s services. But most said they used Fulfillment by Amazon anyway to avoid being punished for late deliveries and other performance issues and because doing so meant their products had more visibility on the site. In the letter, the merchant said Amazon had raised its fees by 20% over the preceding four years until they were 35% more than competing services. Amazon disputed the allegations.