28 United States senators are calling for the Federal Trade Commission (FCC) to halt a net neutrality vote scheduled for later this month over concerns about “fake or fraudulent comments.” In a letter to FCC Chairman Ajit Pai delivered Monday, the senators urged him to postpone the decision.

On December 14, the FCC is slated to vote on whether to suspend Obama-era Title II regulations that protect net neutrality, the principle that internet service providers (ISPs) treat all traffic the same. Many experts regard the regulations as crucial for maintaining an open and free internet. The safeguards are supported by the majority of Americans, while telecom companies and their lobbyists argue they hinder innovation.

The FCC is mostly made up of Republicans who oppose the regulations—Pai was appointed by President Trump—and so it is widely expected that net neutrality will be dismantled later this month when the commissioners vote on the issue. The group of senators, none of whom are Republicans, are worried that the FCC doesn’t actually understand how the public feels about net neutrality because the public record has been flooded with likely fake comments sent by bots.

“We request a thorough investigation by the FCC into reports that bots may have interfered with this proceeding by filing hundreds of thousands of comments,” the letter from the senators reads.

The senators have good reason to be worried about fake comments sent to the FCC, especially those opposing net neutrality. In total, the FCC released nearly 22 million comments submitted through its website during a public commenting period from April 27 to August 30 of this year. The FCC received significantly fewer online comments—only around 4 million—the last time it asked the public to weigh in on net neutrality in 2014.

Over 80 percent of the comments are believed to have been sent by bots, according to an October analysis conducted by the Gravwell, a data analytics company. Most of the automated comments opposed net neutrality, while around 95 percent of “organic,” or believed to be legitimate comments, favored the current regulations.

A more recent analysis conducted by the Pew Research Center released late last month found that over half of comments sent to the FCC contained misleading or false personal information. Some 57 percent utilized either duplicate email addresses, or throwaway addresses meant to “used for a short period of time and then discarded.” 7,500 were affiliated with the email “example@example.com.” Dozens bizarrely referenced the animated film Bee Movie, which became a popular meme earlier this year.

Pew also found that only six percent of the nearly 22 million comments were unique; most were duplicates. The seven most-submitted comments—six of which argued against net neutrality—represented 38 percent of the total comments.

Nine different times, more than 75,000 comments were submitted at the exact same second. Three of the instances included pro-net neutrality comments, and five were anti-net neutrality. The researchers note that many comments were uploaded en masse by advocacy groups, and were not all perpetuated by bots.

The group of senators who sent the letter to Pai are not the only officials concerned about the FCC’s bungled comment process. New York Attorney General Eric Schneiderman has spent six months conducting an investigation into fraudulent comments. He found that hundreds of thousands may have impersonated New York residents, and said that the FCC hasn’t cooperated with requests for more information.

Even members of the FCC itself are concerned. “While I fundamentally disagree with the merits of the FCC’s proposal, what is equally concerning is the lack of integrity to the FCC’s process that has led to this point,” Democratic FCC commissioner Jessica Rosenworcel said in an emailed statement Monday. Rosenworcel also called for the FCC to delay its official vote until official investigations into these anomalies take place.