A resolution in the U.S. Senate that would reverse last month's move by the FCC to kill net neutrality protections nabbed its first Republican backer on Tuesday, but campaigners say that six Democratic holdouts are stilling missing in action if the critical effort is to succeed.

After Sen. Susan Collins (R-Maine) joined 40 Democrats along with Sens. Angus King (I-Maine) and Bernie Sanders (I-Vt.) in supporting a Congressional Review Act (CRA) resolution on Tuesday, the nonprofit group Fight for the Future applauded her decision to side with her constituents, but warned that senators who don't get on board with the effort are backing a deeply unpopular decision.

The group noted that "the overwhelming majority of voters from across the political spectrum" support net neutrality regulations, which keep internet service provides from giving preferential treatment to companies that can afford it, while relegating smaller websites to a "slow lane."

Collins's "support for a Senate vote to block the FCC's repeal of net neutrality shows that this is not a partisan issue, and brings us one huge step closer to restoring basic protections that keep the Internet free from throttling, censorship, and paid prioritization scams," said Evan Greer, campaign director for Fight for the Future, in a statement. "The public has spoken. Lawmakers who stick their heads in the sand on this issue will pay the price at the polls. We will fight lobbyists' attacks on net neutrality every step of the way, and in the end, the Internet will win."

The media reform group Free Press urged supporters to put pressure on the few Democrats who have not announced their support for the CRA.

Political journalists have said the CRA resolution would likely not pass in the Republican-controlled House even if it passes in the Senate, and that it would be subject to a potential veto by President Donald Trump.

But Fight for the Future expressed hope that the growing support for the CRA, as well as the support for internet freedom by 75 percent of Republican voters, could save net neutrality.

As Jon Brodkin of Ars Technica argued this week, advocates are working to keep citizens informed about the implications of the FCC's decision as well as to reverse the vote.

"A vote would keep net neutrality in the spotlight as Democrats prepare to make the repeal a campaign issue in the November elections," he wrote.