(Bloomberg) -- Alphabet Inc.’s Google and Amazon.com Inc. defended their smart-speaker businesses as U.S. senators warned the grip the companies have over the market could harm competition and consumer privacy.

Republicans and Democrats at a hearing Tuesday raised concerns about what they said were anticompetitive practices such as selling devices below cost and promoting their own services over those of competitors on their platforms.

Senator Amy Klobuchar, the Minnesota Democrat who chairs the Senate Judiciary’s antitrust panel, said the expansion of technology giants into more at-home devices risks further consolidating the market, giving an advantage to established players. She cited a scenario of an Amazon device providing customers the option of buying groceries only from Amazon-owned Whole Foods.

“In home technology, we see some of the most powerful firms that dominate tech today poised to dominate the platforms of the future,” she said. “Consumers should choose, not vertically integrated tech giants.”

The hearing marked the latest move by lawmakers on Capitol Hill to scrutinize the practices of the tech industry’s biggest companies as they consider potential reforms to antitrust laws to impose tighter regulations on the companies. Klobuchar and Senator Mike Lee of Utah, the senior Republican on the antitrust panel, have both introduced their own legislation to overhaul and strengthen antitrust enforcement. House lawmakers last week introduced their own proposals.

Eddie Lazarus, chief legal officer for Sonos Inc., said the business practices of Google and Amazon make it hard for the speaker company to compete. He said the companies infringe on 150 patents held by Sonos, among other complaints.

Amazon executive Ryan McCrate testified that Amazon makes its technology available to other developers so that competing music services, for example, are available through its voice-assistant service Alexa. He said Amazon founded a coalition of companies committed to ensuring that consumers have access to multiple, simultaneous voice services on a single device.

Wilson White, a senior director of government affairs at Google, said the company prioritizes consumer choice and privacy. On many devices that use Google’s Android operating system, consumers can choose to set up rival voice assistants like Alexa, he said.

Lee cautioned against giving tech companies even more power to steer consumer choices as new products enter the home.

“Why would be want to give big tech more control and more influence over our daily lives? We know they don’t always exercise this power in the best interest of society,” Lee said. “Surely we know enough to know this isn’t going to end well.”

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