WASHINGTON (Reuters) – A group representing major technology firms including Alphabet Inc (GOOGL.O) and Facebook Inc (FB.O) urged the U.S. Federal Communications Commission on Monday to abandon plans to reverse the landmark 2015 rules barring internet service providers from blocking or slowing consumer access to web content.

The Internet Association said in its filing with the FCC that dismantling the net neutrality rules “will create significant uncertainty in the market and upset the careful balance that has led to the current virtuous circle of innovation in the broadband ecosystem.”

The rollback will harm consumers, said the group, which also represents Amazon.com Inc (AMZN.O), Microsoft Inc (MSFT.O), Netflix Inc (NFLX.O), Twitter Inc (TWTR.N) and Snap Inc (SNAP.N).

In May, the FCC voted 2-1 to advance Republican FCC Chairman Ajit Pai’s plan to reverse the former Obama administration’s order reclassifying internet service providers as if they were utilities.

Pai has asked if the FCC has authority or should keep its rules barring internet companies from blocking, throttling or giving “fast lanes” to some websites, known as “paid prioritization.”

Pai, who argues the Obama order was unnecessary and harms jobs and investment, has not committed to retaining any rules, but said he favors an “open internet.”

The Internet Association said there was “no reliable evidence” provider investment had fallen.

More than 8.3 million public comments have been filed on the proposal. Pai will face questions on Wednesday on the issue at a U.S. Senate hearing.

Broadband providers AT&T Inc (T.N), Verizon Communications Inc (VZ.N) and Comcast Corp (CMCSA.O) opposed the 2015 order, saying it discouraged investment and innovation.

Providers say they strongly support open internet rules and will not block or throttle legal websites even without legal requirements. They separately plan to file comments with the FCC on Monday.

But some providers have said paid prioritization may make sense at times, citing self-driving cars and healthcare information.

Internet firms say opening the door to prioritization could enable providers to “destroy the open nature of the internet that allows new or smaller streaming video providers to compete with larger or better-funded edge providers.”

Internet providers want Congress to resolve the decade-old dispute and pass open internet protections, but narrowly tailor rules to exclude a future FCC from imposing rate regulations.

The Internet Association said it was “open to alternative legal bases for the rules, either via legislative action codifying the existing net neutrality rules or via sound legal theories offered by the commission.”

But it said Pai’s proposal “offers no clear alternatives.”