A sweeping plan to roll back Obama-era rules intended to ensure an open internet has drawn a record number of comments before a critical vote by the Federal Communications Commission (FCC).

With hours left before the window for public feedback closes on Wednesday, the agency has received nearly nearly 22m comments on “Restoring Internet Freedom”, which could dismantle net neutrality rules put in place in 2015. Though many of the comments appear to be from spambots, the effort to ease regulations on internet service providers (ISPs) has drawn widespread criticism from Democrats, consumer advocates and internet companies.

The FCC, led by Republican chairman Ajit Pai, voted in May to start the formal process of unwinding the 2015 rules. Those rules treat regulation of internet more like that of a public utility such as water or electricity and prohibit broadband providers such as Verizon and Comcast from creating a tiered system of access.

Under the current net neutrality rules, it is illegal for companies to offer a high-speed lane to corporations able to pay more or to effectively slow a rival service.

The FCC’s proposal asks whether the agency should eliminate the rule banning ISPs from creating fast lanes (or slow lanes) that could favour one service over another, which critics say could allow them to pick winners and losers online. Pai has said the regulations stifle corporate innovation and investment and are not necessary to guaranteeing an “open internet”.

Major cable companies have applauded the plan and say they are encouraged by Pai’s intention to take a “weed-whacker” to the net neutrality rules and replace them with “light-touch” regulation.

The proposal has set in motion a complex fight over the future of the internet. This summer, nearly 200 internet companies, including Facebook, Google and Amazon, led an internet-wide day of action to mobilize users against the FCC’s plans to scrap net neutrality.

Comedian John Oliver has also helped spotlight the issue and after he highlighted the FCC’s proposal on his show, Last Week Tonight, the agency’s website crashed. The regulator has claimed it was attacked by hackers but has yet to provide evidence.

The FCC’s comment page appears to have been flooded by fake, often identical, comments in support of repeal. In a letter to the FCC, coordinated by internet activists Fight for the Future, the group estimates that as many as 450,000 of the comments on FCC’s website may be spam created by enemies of net neutrality.

Evan Greer, campaign director for Fight for the Future, said: “The unprecedented number of comments in the FCC docket underscores what everyone already knows: people freakin’ love the free and open internet and are willing to fight tooth and nail to defend it.

“With the FCC public comment period closing, all eyes shift to Congress: will our lawmakers represent us and speak out against the FCC’s plan to gut protections for free speech and innovation, or will they use this opportunity to launch a cynical attack on internet users’ rights under the guise of ‘compromise’ legislation?”

When the comment period ends on Wednesday night, the agency will analyze the responses and assess whether they should adjust their proposal accordingly. The FCC is next scheduled to meet on 28 September, though they are unlikely to take a vote on the plan then.