WASHINGTON — Federal officials took aim at a signature Obama-era regulation Tuesday, unveiling a plan that would give internet service providers broad powers to determine what websites and online services their customers see and use.

Under the proposal by the Federal Communications Commission, companies that provide high-speed internet services, such as Comcast, Verizon or AT&T, would be able to block web content they do not like and auction off speedier delivery of content to the highest bidder.

The move is one of the more significant deregulatory efforts by Republicans since President Trump took office. Ajit Pai, who was nominated to head the FCC by Trump in January, has said undoing the “net neutrality” regulations passed by his predecessor was one of his top priorities.

Those rules were passed in 2015 by a Democrat-led FCC that said it wanted to make sure all content, whether from big or small companies, would be treated equally by internet providers.

But Pai argued that those rules stifle innovation and amount to government overreach.

“Under my proposal, the federal government will stop micromanaging the Internet,” Pai said in a statement Tuesday. The plan could be approved by the Republican-led FCC as early as its Dec. 14 meeting.

Pai’s remarks were cheered by conservatives as well as cable, broadband and wireless companies, which provide most of the internet service to American homes, smartphones and other devices.

“It’s a signature accomplishment for Pai’s chairmanship,” said Fred Campbell, director of the conservative think tank Tech Knowledge. “This item represents the starkest policy difference between the Obama FCC … and chairman Pai.”

Added Verizon in a statement: “We’re very encouraged by Chairman Pai’s announcement today that the FCC will move forward next month to restore the successful light-touch regulatory framework for Internet services,” Verizon said in a statement.

But Pai’s announcement set off a firestorm of criticism from internet companies and activists who vowed to hold demonstrations before the FCC’s vote.

The Free Press Action Fund and other consumer activist groups said they would organize protests outside Verizon stores, and accused Pai of doing the company’s bidding. Pai served as an associated general counsel at Verizon for two years beginning in 2001.

Former Democratic FCC chairman Tom Wheeler, who drafted the 2015 net neutrality rules, called Tuesday’s move “tragic,” adding that “if you like your cable company, you’ll love what this does for the internet.

“The job of the FCC is to represent the consumer,” he said in an interview. “Tragically, this decision is only for the benefit of the largely monopoly services that deliver the Internet to the consumer.”

Technology giants are expecting to lobby furiously against the FCC’s plan, setting up a heavyweight fight between Silicon Valley giants and telecommunications conglomerates – two of the most well-heeled industries in the country.

“The FCC’s net neutrality rules are working well for consumers, and we’re disappointed in the proposal released today,” Google said in a statement.

Pai’s plan would require internet service providers to be transparent about their practices.

For example, if a provider chose to block or slow certain websites, or gave preferable treatment to content that it owned or had partnerships with, that provider would have to inform consumers of its policy on an easily accessible website.

Violations of the transparency rule could lead to fines by the FCC, said senior agency officials, who spoke on the condition of anonymity to discuss the matter more freely.

The proposal also would shift some enforcement responsibility to the Federal Trade Commission, which can sue companies for violating the commitments or statements they have made to the public.

Relying more heavily on the public promises of internet providers is a departure from current net neutrality rules, which lay out clear bans against selectively blocking or slowing websites, as well as speeding up websites that agree to pay the providers fees.

Repealing those rules will allow internet providers to experiment with new ways to make money. In recent years, some broadband companies, such as AT&T, have tried offering discounts on internet service to Americans as long as they agree to let the company monitor their Web browsing history, for example.

Other companies, such as Verizon, have exempted their own apps from mobile data limits in a bid to drive user engagement.

Allowing the FTC to police broadband providers’ own promises is tantamount to providing “toothless protections,” consumer advocates say.

Matt Wood, policy director for the advocacy group Free Press, likened the proposed system to the way that many companies design their privacy policies.

“You need only look to how privacy policies from websites allow essentially any and all bad behavior,” he said, “so long as it is disclosed to users.” Maureen Ohlhausen, the acting chairman of the FTC, has said that the agency’s expertise in data security and privacy issues will make it a powerful defender of U.S. consumers.

“The FTC stands ready to protect broadband subscribers from anticompetitive, unfair, or deceptive acts and practices just as we protect consumers in the rest of the Internet ecosystem,” Ohlhausen said in a statement Tuesday.

One major beneficiary of the FCC’s rule-change may be AT&T, which is in a major legal dispute with the Justice Department over an $85 billion purchase of the entertainment conglomerate Time Warner. Should AT&T’s acquisition of Time Warner be allowed to close, a repeal of the FCC’s net neutrality rules would give the telecom giant greater power to promote its new content properties in a myriad of ways, some analysts say.

The FCC’s proposal also adds pressure on Capitol Hill, where some lawmakers have called for federal legislation that would supersede any FCC rules.

On Tuesday, Sen. John Thune, R-S.D., praised Pai’s effort but renewed his call for a bipartisan compromise on net neutrality, saying it is the only way to “create long-term certainty for the Internet ecosystem.”