Maine Sens. Susan Collins and Angus King announced Tuesday that they would back a Democrat-led effort to restore the Obama administration's "net neutrality" rules, with Collins' announcement giving the move Republican support.

Democrats have said they have the support necessary to force a Senate vote under the Congressional Review Act.

"She believes that a careful, deliberative process involving experts and the public is warranted to ensure that consumers have strong protections that guarantee consumer choice, free markets and continued growth," Collins' spokeswoman Annie Clark told the Bangor Daily News.

King, an independent, tweeted Tuesday that he was backing the bill, which is authored by Sen. Ed Markey, D-Mass. "I support @SenMarkey’s bill to defend #NetNeutrality, which is critically important to a free and open internet," said the senator, an independent who caucuses with the Democrats.

They were the first two non-Democrats to back Markey's effort, putting the number of co-sponsors at 43. Markey declared Monday they had sufficient support to force the Senate leadership to schedule a vote on the resolution. The effort nevertheless remains a longshot. While the Congressional Review Act allows a majority in Congress to rescind regulations, the bills can be vetoed by the president. Supermajorities in both houses of Congress are needed to override a veto.

"@SenateGOP will finally have to choose: side with 83% of the American people, or pay the political price for being on the wrong side of history," Markey tweeted.

The Federal Communications Commission, led by Chairman Ajit Pai, last month rolled back Obama-era rules that classified the Internet as a public utility required to treat all content, platforms, and sites equally. Net neutrality prevents service providers from blocking Internet traffic or charging different fees for services. Pai argued the Obama regulation limited competition and slowed investment in new networks, leaving consumers worse off. Critics contend the move gives too much power to larger providers.

The move has been extremely controversial. Pai canceled an appearance at the annual Consumer Electronics Show Las Vegas on Tuesday following death threats directed at him over the issue.