Federal Communications Commission chairman Ajit Pai—a former Verizon lawyer appointed by Trump as the nation’s top telecommunications regulator in January—is expected to unveil his approach for rolling back the 2015 net neutrality rules during a speech on Wednesday.

But hours before Pai is scheduled to take the dais at the Newseum in Washington, D.C., several Democratic senators who support the rules outlined how they would seek to rally public support and try to save the rules.

“There are steps we can take to stop it,” Sen. Richard Blumenthal (D-Conn.) told reporters on Wednesday morning. “We need to mobilize and galvanize the seismic outcry and outrage that should follow this kind of misguided effort. Second, there are legal recourses…I will oppose this effort wherever possible, in the Commerce Committee, on the floor of the Senate, and help in the courts if necessary.”

Federal courts have closely scrutinized FCC efforts to protect net neutrality over the past decade. Two earlier efforts were struck down by the courts as lacking adequate backing in law, until the most recent 2015 plan was upheld last year. But in all three prior cases, it was one or more of the big communications companies that sued to block the rules.

The FCC chairman has floated a plan to replace the FCC’s mandatory rules with voluntary pledges by Internet service providers, which would be policed not by his agency but by the Federal Trade Commission.

But voluntary rules wouldn’t be an adequate substitute, Sen. Ed Markey (D-Mass.) said on the call. “It’s only with enforceable rules–not voluntary–that we can prevent the few and powerful Internet service providers from serving as Internet gatekeepers choosing winners and losers online.”

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The current rules prohibit Internet service providers from blocking or slowing access to any web site, or otherwise discriminating against online sites and services.

Otherwise, it might be possible for an Internet service provider like Comcast, which also sells cable TV, to slow down customers’ access to services like Dish Network’s (DISH) Sling TV or Google’s (GOOGL) YouTube TV that compete using Internet apps. In 2008, the FCC sanctioned Comcast (CMCSA) for slowing customers’ access to the video sharing network BitTorrent, for example, though a court later struck down the decision.

And Netflix (NFLX) fought with cable providers for years trying to intentional streaming slowdowns and extra fees for connecting with its customers.

But the big Internet service providers say the 2015 rules are too burdensome, deterring them from investing to speed up their networks, and preventing them from offering customers the best deals and services.

Pai and his allies in Congress have moved quickly to reverse many Obama-era FCC rules and policies opposed by major telecommunications and media companies like Verizon (VZ), AT&T (T), and Comcast. Last week, Pai lifted price limits on Internet service for small businesses, libraries, and schools and eased restrictions on how many TV stations one company can own.

Earlier, he dropped an effort to create competition for cable TV set-top boxes and cancelled investigations into whether Verizon and AT&T had violated the net neutrality rules by favoring their own streaming video services.

According to several reports, Pai will next outline his strategy for reversing the FCC’s net neutrality rules in his speech on Wednesday. But the effort could take longer than some of Pai’s earlier moves. Under Obama-appointed chairman Tom Wheeler, after courts had struck down two earlier efforts, the agency spent months crafting the rules following an exhaustive public comment period.