The push to take down the Federal Communications Commission’s broadband privacy rules ramped up Thursday as 21 free-market groups called on congressional leaders Thursday to “rescind” the regulations using the Congressional Review Act.

Their request comes as lawmakers are considering a range of Obama administration rules that they think can be rescinded using the 1996 law. The privacy rules are not on the list.

“Congress is fully justified in rescinding these rules both because the Order lacks proper legal grounding and because of the need to ensure real consumer privacy across contexts of user experience,” the groups wrote in a Thursday letter to House Speaker Paul Ryan (R-Wis.), House Democratic Leader Nancy Pelosi (Calif.), Senate Majority Leader Mitch McConnell (R-Ky.) and Senate Democratic Leader Chuck Schumer (N.Y.).

TechFreedom, Digital Liberty, Americans For Tax Reform and FreedomWorks were among the organizations that signed the letter.

The privacy rules, passed by the FCC on Oct. 27, require internet service providers to receive explicit consent from customers before they use “sensitive” data, including a user’s web browsing or app usage history for marketing purposes.

Republicans at the FCC, GOP lawmakers and leaders in the broadband industry have criticized the rules because they break with the Federal Trade Commission’s framework for regulating privacy at internet companies such as Facebook Inc. and Amazon.com Inc.

The FTC’s approach does a “better job” of balancing consumer privacy and companies’ ability to use data to make money, and therefore improve their services, the groups said.

Rep. Frank Pallone (D-N.J.) House Energy and Commerce Committee, condemned the letter in a Thursday statement, saying “consumers should not have to worry about their financial, medical and other personal information being shared without their permission.” Pallone said he would fight the effort.

The CRA is only one option for rolling back the privacy rules. They hinge on the FCC’s reclassification of internet service providers as common carriers through its 2015 net neutrality rules. The FCC was able to implement the privacy rules. Now, the entire net neutrality could be rescinded under Republican Chairman Ajit Pai.

There is also a possibility that broadband companies will appeal to the Supreme Court to reverse a federal court’s decision last June to uphold the rules.

In Thursday’s letter, the free-market groups argued that the legality of the FCC’s net neutrality rules is “questionable.”

Several petitions from industry groups such as USTelecom and the Internet and Television Association filed petitions with the FCC in early January urging the agency to roll back its privacy rules.