WASHINGTON (CN) – Democratic Senators assailed U.S. Supreme Court nominee Brett Kavanaugh on Tuesday, claiming his past position on net neutrality – that it unconstitutionally infringes on the First Amendment rights of internet service providers – is but another reason why his nomination should be refused.

Kavanaugh’s confirmation to the Supreme Court is considered almost a certainty, with Democrats having little to no chance of blocking it. However on Tuesday, Democratic Sens. Ed Markey, of Massachusetts, Ron Wyden, of Oregon, Richard Blumenthal, of Connecticut, and Anna Eshoo, of California, issued a stern warning about the nominee and the “threat” they believe he poses to the future of an open internet.

They base their contention on a dissent Kavanaugh wrote in May 2017, when a three-judge appellate panel ordered the Federal Communications Commission to keep net neutrality rules in place.

Net neutrality, or the concept that internet service providers should not throttle information or access online, was first established by FCC regulation in 2015. Known formally as the Open Internet Order, it was reversed by a deeply-divided commission last year.

In his criticism of the regulation, Kavanaugh once wrote that net neutrality “impermissibly infringes” on the “editorial discretion” of internet service providers.

He went on to write that the Obama-era FCC’s decision to enforce net neutrality was unconstitutional because the rule was never formally authorized by Congress and therefore undermined the separation of powers.

On Tuesday, Sen. Ed Markey said on a call with reporters that the most “dangerous” element to Kavanaugh’s stance on net neutrality is his assertion that broadband carriers have First Amendment rights.

“A broadband carrier, like any other common carrier, is obligated to provide nondiscriminatory and equal access to its consumers. The courts have recognized that a broadband provider is merely facilitating the transmission of others’ speech and is not engaged in speech of own. Just because someone uses a soap box doesn’t mean the soap box has First Amendment rights,” Markey said.

Kavanaugh’s view that internet service providers should be considered individuals entitled to free speech instead of the “mere conduits” for other’s speech, leads only to one place, the senator said.

“Mark my words the fate of the internet will end up in the Supreme Court and if Kavanaugh is there, he will kill net neutrality rules forever,” Markey said.

The FCC’s repeal of net neutrality has triggered multiple legal challenges.

On Monday, two top telecommunication trade groups, the Internet Association and the Computer and Communications Industry Association, filed a brief supporting reversal of the repeal in a federal appeals court in Washington, D.C.

The trade groups, who represent companies like Facebook, Amazon and Google, asked the court to reinstate the 2015 regulation.

They argued that without the rule, “the virtuous cycle in which all participants in the internet ecosystem are able to prosper on account of open access,” ultimately ceases to exist.

By striking down the regulation, “a system in which ISPs have the incentive and ability to stifle both consumer choice and new online offerings,” continues to emerge, the groups said.

The senators, along with 27 of their colleagues and 76 members of the House of Representatives, filed an amicus brief Monday supporting 23 attorneys general who have challenged the repeal.

Sen. Ashoo said Kavanaugh’s position on net neutrality is particularly worrisome when considering the “real time effect” of giving ISPs more control over internet access.

The Mendocino Complex fire in Sacramento, California earlier this month – where first responders internet access was throttled, leading to a reduction in data for over 24 hours – is a prime example of how large ISPs, “without clear enforceable rules of the road” hurt consumers, she said.

Gigi Sohn, attorney for former FCC chairman Tom Wheeler and one of the authors who drafted the original net neutrality rules, was also on the call Tuesday.

“Even when the Supreme Court ruled in 2005 that the FCC has discretion for how ISPs should be regulated, Kavanaugh didn’t believe it then. Ironically, he credits the major rules doctrine to Justice Antonin Scalia,” Sohn said.

Scalia dissented in the National Cable and Telecommunications Association v. Brand X Internet Services case, Sohn explained.

Scalia specifically said that the Telecommunications Act of 1996 – which set the stage for net neutrality rules over a decade later – were “clear and unambiguous” when it came to whether ISPs were barred from discriminating against consumers.

“Kavanaugh believes [net neutrality] rules violate the First Amendment because there is ‘vibrant competition in the market for internet access,’” His opinion reflects a clear misunderstanding of the First Amendment in the communication space, Sohn said.