Democrats are trying to pressure the Federal Communications Commission (FCC) at the eleventh hour to call off its planned vote to scrap its net neutrality regulations.

The vote is planned for Thursday and the repeal proposal is expected to pass along party lines.

On Tuesday, 39 senators sent a letter to FCC Chairman Ajit Pai urging him to call off his "reckless" proposal to eliminate the Obama-era regulations.

"Your plan gives a broadband provider the ability to significantly alter their subscribers' internet experience," the letter reads. "Once adopted, this proposal will permit that provider to freely block, slow down or manipulate a consumer's access to the internet as long as it discloses those practices - no matter how anti-consumer - somewhere within mounds of legalese in a new 'net neutrality' policy."

And across the Capitol, Rep. Mike Doyle (D-Pa.) on Tuesday promised to introduce legislation after the vote that would roll back Pai's plan.

The net neutrality rules bar internet service providers from slowing down or favoring any web content.

Republicans largely blast the rules as a heavy-handed regulatory approach that stifles investment and innovation, while Democrats see them as essential for preserving the free flow of information on the web.

The last-ditch effort is unlikely to sway Pai, who has vowed to move forward with the repeal vote. His plan would give the Federal Trade Commission (FTC) the authority to police broadband companies for any unfair or deceptive behavior. He argued the proposal would require the industry to be transparent about its practices and that the FTC is equipped to make sure that companies like Verizon and Comcast don't abuse their powers over web traffic.

"Instead of saddling the Internet with heavy-handed regulations, we will work together to take targeted action against bad actors," Pai said Monday as the two agencies unveiled a blueprint for how they will police the internet after net neutrality.

"This approach protected a free and open Internet for many years prior to the FCC's 2015 Title II Order and it will once again following the adoption of the Restoring Internet Freedom Order," he added.

But Democrats argue that the FTC, a consumer protection agency, doesn't have the expertise to police telecom companies and that its mandate is only to crack down on deceptive or anticompetitive practices.

Democrats have also accused Pai of rushing his proposal through amid questions about pervasive fraudulent comments in the FCC's public record.

Last week, the agency's general counsel rejected New York Attorney General Eric Schneiderman's (D) information requests about fake comments and whether some were filed under stolen identities.

The FCC's top lawyer, Thomas Johnson, argued that the existence of fake comments is largely irrelevant since none of them were cited when Pai crafted his proposal to roll back the rules.

Pai's plan enjoys broad support among congressional Republicans, who are unlikely to join any legislative efforts to block the repeal. The GOP wants Democrats to join them in coming up with a legislative replacement to the rules, but many Democrats have balked at swapping the FCC rules for a bill they believe would fall short.