Republican Sen. Josh Hawley on Monday issued a rare rebuke of the government agency that oversees Facebook, Google and other tech giants, charging that regulators had “failed” to protect consumers and their personal data from abuse.

In a letter to the Federal Trade Commission, the Missouri lawmaker urged the agency’s leaders to take a more aggressive stand toward Silicon Valley, starting with investigations into tech companies for violating their users’ privacy repeatedly over the past year.

Hawley said there is “substantial evidence” that Facebook had broken a 2011 agreement with the FTC that settled an earlier probe into its privacy practices — a breach that could trigger steep federal fines. The GOP senator also faulted Facebook for its earlier efforts to monitor kids’ and adults’ app usage through a tool that was loaded onto iPhones in a way that angered Apple.

With Google, meanwhile, Hawley charged that the search giant had “consistently misinformed users about its use of geolocation data,” at times collecting that information from Android smartphones even when device owners thought they had disabled the tracking of their whereabouts.

Read Missouri Senator Josh Hawley's letter to the FTC

In response to these and other high-profile privacy mishaps, Hawley said the FTC so far “has been toothless,” and he urged the agency to use all the power at its disposal to probe big tech companies — or tell Congress if it’s outmatched and needs help.

"For too long our nation has put off accounting for the price we paid in return for the benefits of the online platforms that now dominate American culture and industry,” Hawley wrote to FTC Chairman Joe Simons, a fellow Republican.

"These companies have failed us. Washington has failed us. The FTC has a special role to play, but it too has failed us,” Hawley said.

Hawley’s missive arrives a day before the Senate Judiciary Committee, of which he is a member, is set to hold a hearing about online privacy and the future of regulation. Google is expected to testify at the Tuesday session, according to two sources familiar with the matter but not authorized to speak on the record, along with representatives from other tech companies and consumer groups. A spokesman for the panel’s chairman, GOP Sen. Lindsey O. Graham (S.C.), did not respond to a request for comment.

Facebook and Google also did not immediately respond to requests for comment. The FTC has been probing Facebook over its entanglement with Cambridge Analytica, a political consultancy that improperly accessed data on 87 million of the social site’s users — but Facebook has denied it broke its accord with the agency. Google has said it provides clear tools to control what happens to users’ location data.

More than a century old, the FTC serves as the U.S. government’s de facto privacy cop because of its mandate to police businesses for unfair or deceptive acts and practices. In recent months, the agency has taken action on issues including children’s privacy, levying a fine against the social app now known as TikTok, and it created a special task force to oversee competition in the tech industry. A spokesman for the FTC did not immediately respond to a request for comment.

Still, the FTC has faced fierce criticism across the political spectrum for failing to penalize wrongdoers in the tech industry. Roughly a dozen consumer-privacy organizations in January called on Congress to create an entirely new “federal agency focused on privacy protection, compliance with data protection obligations, and emerging privacy challenges.” Some of those groups, led by the Electronic Privacy Information Center, have urged the FTC to complete its probe into Facebook and Cambridge Analytica before its one-year anniversary later this month.

On Capitol Hill, the agency’s future also has received renewed attention as Democrats and Republicans have started to discuss new legislation targeting the data-collection practices of Facebook, Google and other tech giants. The United States lacks an overarching federal consumer privacy law, even though individual states, led by California, have adopted their own rules — and Europe leads the world as the toughest regulator of tech companies.

Democrats generally have called for granting the agency stronger authorities, along with more money and new staff, to police privacy abuses. Republicans historically have been more reluctant to give the commission new power — but increasingly have expressed an interest in rethinking the agency role on data-protection issues.

In his letter, Hawley asked the FTC to detail whether it had gaps in its authorities that stymied its work — but urged it to wield the power it already has to probe privacy abuses by the country’s largest tech companies.

“These debates cross party lines, implicating election integrity, free speech, privacy, competition, and many other issues,” he wrote. “But these debates include a central, shared concern that the new custodians of once-diffuse information have abused the power they amassed and neglected their responsibilities.”