Concern about the commission relaxing the law’s privacy provisions has led to a rare moment of bipartisan cooperation: Two Democratic senators, Ed Markey of Massachusetts and Richard Blumenthal of Connecticut, have joined two Republican senators, Josh Hawley of Missouri and Marsha Blackburn of Tennessee, in calling on the commission to hit the brakes. In an interview, Mr. Hawley said about the practice of targeting ads to children based on their previous online behavior, “I’m concerned about some of the comments that F.T.C. officials have made where they seem to suggest that behavioral-targeted advertising is a good thing.” He added, “I mean, that sounds frankly crazy to me.”

One such official is Andrew Smith, director of the F.T.C.’s Bureau of Consumer Protection, who has echoed industry talking points about how increased privacy protections could hurt the internet experience. He went off script at a Better Business Bureau conference last month to say that if creators are unable to monetize their content with behaviorally targeted ads (to which children are particularly vulnerable), YouTube would become “a desert of crap.” That prompted privacy advocates to call for his recusal from rule-making on the issue.

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The senators are concerned about the commission’s spotty record of enforcing compliance with COPPA, and warned in their letter to the commissioners that the “F.T.C. is at risk of favoring the interests of giant tech companies over the interests of parents and children.”

Mr. Hawley and Mr. Markey have co-sponsored a legislative update to COPPA that includes an “Eraser Button” that would give parents the power to delete their children’s data. It also would raise the age covered by the law to 15 from 12, as well as tighten the requirement that a website seek parental consent to collect information if it has reason to believe a viewer is a child. The current standard is looser, and companies like Google and its subsidiary YouTube have abused it, knowingly targeting children for advertising .

Just last month, the commission fined Google and YouTube $170 million for violating the children’s privacy law by harvesting children’s personal data and using it to target them for ads using cookies . While it was by far the F.T.C.’s largest privacy fine leveled to date, it was a small sum for such flagrant violations. In Mr. Hawley’s opinion, “The F.T.C. has just, in the last two months, gone very easy on YouTube and Google over blatant and widespread violations of COPPA.”

The Markey-Hawley bill would give the commission clear direction on how to enforce the law, limiting the power of industry lobbyists and lawyers to influence agency decisions.