The news: DoorDash’s roughly $17 billion acquisition of Instacart is worrying some merchants who fear the combined company could use its increased market power to extract more revenues from their businesses, per Business Insider.

The conundrum: For many grocers, the delivery services offered by Instacart and DoorDash—as well as Uber Eats—are the only way they can compete against the ecommerce capabilities of Amazon and Walmart. Though many grocers have deals with multiple companies, the elimination of one of their three major options could give the remaining players room to charge more for their services or prioritize larger retail partners over local grocers.

For example, Stew Leonard Jr., CEO of the Stew Leonard’s grocery chain, told BI that he has been able to pick between DoorDash and Instacart depending on which offers better terms. Both companies have also worked closely with the grocer to grow online orders through promotions and advertising, but Leonard questioned whether that support would continue should the two combine, especially given its relatively small footprint.

Other companies are concerned that higher commission fees could result in higher prices for shoppers who use Instacart and DoorDash to shop. That markup would further constrain independent and smaller grocers’ ability to compete amid growing market consolidation: Instacart executives have repeatedly emphasized that retailers who offer the same prices on its marketplace as on their own sites consistently grow faster and retain customers better than those that don’t—but that option is more readily available for larger retailers that have the funds to invest in price parity.

The opportunity for Uber: The acquisition doesn’t worry Uber, which sees an opportunity to attract merchants trying to avoid dependence on a single delivery system, CEO Dara Khosrowshahi said on the company’s Q3 earnings call.

Khosrowshahi pointed to Uber’s fast-growing grocery and retail business as proof of its ability to hold its own against DoorDash and Instacart. The segment is growing 40% and generating revenues at a $15 billion run rate, he said, and has runway to expand as the company improves product selection, quality, and the delivery experience. Our forecast expects Uber’s grocery business to grow nearly three times as fast as DoorDash’s and Instacart’s this year and maintain faster growth than its competitors into 2028.

Merchants “want plenty of partners, including us and DoorDash and Instacart, to work with,” Khosrowshahi said. At the same time, some are “very worried about the potential transaction” and are deepening their partnership with Uber to avoid having too much of their business tied to a single operator.

Implications for retail: DoorDash is hoping that a merger-friendly Trump administration will approve the acquisition with minimal disruptions—but it could face a more protracted fight now that Democrats will take control of both the House and Senate next year. With affordability and cost-of-living central to the party’s agenda, deals like the Instacart acquisition that could affect grocery prices are likely to face heightened scrutiny, even if Democrats currently lack the ability to challenge the deal at the federal level.

Uber stands to benefit in the short term as it signs on more retail partners who are worried about the potential for higher costs from the acquisition and keeping pace with Walmart and Amazon. Both DoorDash and Instacart will have to focus on shoring up relationships with their retail partners to ease their concerns and get their buy-in for the deal.

Regardless of whether the acquisition is approved, partnerships with DoorDash and Instacart will remain a cost of doing business for grocers navigating a market dominated by Amazon and Walmart, which we expect to control over three-quarters of US grocery ecommerce sales this year.