WASHINGTON — Senators pressed top antitrust regulators on Tuesday to aggressively investigate the power of the country’s biggest tech companies, with some lawmakers questioning whether the officials had the will or resources to take on Silicon Valley’s richest businesses.
In the regulators’ first hearing since the Federal Trade Commission and the Justice Department divided up antitrust responsibilities for Amazon, Apple, Google and Facebook, lawmakers pushed for assurances that the agencies would provide vigorous oversight of the companies.
But the regulators — Joe Simons, the chairman of the trade commission, and Makan Delrahim, the top antitrust official at the Justice Department — offered few details about their inquiries into the industry. That frustrated some of the lawmakers at the hearing, held by the Senate Judiciary subcommittee on antitrust.
“The fact that you’re coming here without any specifics I think reinforces the impression that federal antitrust enforcement is an empty suit,” said Senator Richard Blumenthal, a Democrat from Connecticut. “What the public sees is a facade with respect to Big Tech — and no immediate prospect of urgency or active enforcement.”
The tech giants are embroiled in investigations around the world over concerns they have abused their market power. In the United States, federal agencies and House lawmakers are looking into the power and influence of Apple, Amazon, Google and Facebook. Many state attorneys general have announced investigations into Facebook and Google.
The scrutiny has helped upend the companies’ usual place in Washington, where they have long been cheered on as pillars of innovation and a major engine of the country’s economy. The companies’ troubles have escalated in recent years from a range of scandals, including how they handle consumer data and their role in spreading disinformation during the 2016 presidential election.
In July, the Federal Trade Commission approved a fine of roughly $5 billion against Facebook for mishandling users’ personal information, by far the largest fine against a technology company in the United States. But Senator Josh Hawley, a conservative Republican from Missouri, on Tuesday questioned Mr. Simons of the F.T.C. about whether the settlement was too weak.
Mr. Hawley homed in on the fact that the agency never talked to Facebook’s top executives during the privacy investigation, using it to suggest that there could be a lack of determination at the agency.
“Did you interview Mark Zuckerberg during your investigation?” Mr. Hawley asked Mr. Simons. “Did you interview Sheryl Sandberg during the investigation?”
Mr. Simons answered no to both questions.
Concerns about the tech companies vary. Facebook is accused of shutting out nascent competitors. Google has drawn scrutiny for its smartphone software, ad and search businesses. Critics say Amazon uses its knowledge of independent merchants on its platform to make competing generic products. And software developers chafe at Apple’s status as a gatekeeper for iPhone apps.
At the federal level, Mr. Simons and Mr. Delrahim have divided up responsibility for handling antitrust complaints about the companies. The Justice Department took Google and Apple, and the F.T.C. got Facebook and Amazon.
The regulators and companies have confirmed only two formal investigations. Google disclosed in August that it had received a formal request from the Justice Department for information related to a previous investigation of the company, signaling a new inquiry was underway. Facebook is the subject of an F.T.C. antitrust investigation related to its acquisition of other services.
But the accord between the agencies appears tenuous. Lawmakers pressed the regulators on Tuesday on reports that they were at odds over the investigations.
When Senator Mike Lee, Republican of Utah, said it sounded like “things have broken down at least in part” between the agencies, Mr. Simons replied: “I would agree with that.” Asked later to expand on his comments, Mr. Simons declined.
Mr. Delrahim also acknowledged that there was some overlap on the tech investigations. And he said that the state attorneys general investigations could complicate matters, too.
“I think at the early stage we’ve got to make sure that we’re not tripping over each other,” said Mr. Delrahim, calling discussions with the states “productive.”
Senator Amy Klobuchar, a Democrat from Minnesota and a presidential candidate, said her concern was not of multiple agencies looking into one company — but that the companies do not get enough scrutiny.
“I just look at this is in such a different way,” she said. “I’d rather have a split investigation than no investigation.”
Mr. Lee expressed another concern: that the investigations would start to look like those in Europe. Regulators in Europe have been far more aggressive about bringing antitrust cases against the tech companies. But Mr. Lee warned that the motivations were not necessarily to protect consumers.
“The primary concern” in Europe, he said, “seems to be protecting competitors rather than competition itself.”