Tech startups are launching an effort to persuade the Federal Communications Commission (FCC) not to change its net neutrality rules.

Major Silicon Valley startup accelerators Y Combinator and Techstars, as well as startup advocacy group Engine, are circulating a letter asking FCC Chairman Ajit Pai to leave in place the net neutrality rules passed under former Chairman Tom Wheeler in 2015, formally known as the Open Internet Order.

{mosads}The Hill and other outlets have reported that Pai is expected to reveal his plans to curb at least some portions of net neutrality, including a provision that allows the FCC to regulate broadband providers, by the end of May.

In the letter, first reported by Axios, the groups express concern about Pai’s reported plans.

“In 2015 the Federal Communications Commission put in place light touch net neutrality rules that not only prohibit certain harmful practices, but also allow the Commission to develop and enforce rules to address new forms of discrimination,” they wrote.

“We are concerned by reports that you would replace this system with a set of minimum voluntary commitments, which would give a green light for Internet access providers to discriminate in unforeseen ways.”

The groups argued that Pai’s potential moves to alter the rules could be an existential threat to the startups that they support.

“The success of America’s startup ecosystem depends on more than improved broadband speeds. We also depend on an open Internet — including enforceable net neutrality rules that ensure big cable companies can’t discriminate against people like us. We’re deeply concerned with your intention to undo the existing legal framework.”

The groups plan to send the letter to Pai’s office on May 1.

Y Combinator President Sam Altman penned a blog post in March voicing his support for net neutrality’s reclassification of broadband companies as common carriers. This reclassification gives the FCC the jurisdiction to regulate internet service providers.

“The internet is a public good, and I believe access should be a basic right,” Altman wrote. “It seems best to keep it regulated like a common carrier. Doing this allows the government to ensure a level playing field, impose privacy regulations, and subsidize access for people who can’t afford it.”

Other groups have also been readying themselves for the forthcoming fight over the rules. Earlier this week, tech trade association the Internet Association — which lobbies on behalf of companies like Google, Facebook and Amazon — met with the FCC to support the net neutrality rules in their current form.

Pro-net neutrality consumer groups have begun to take preliminary steps like calling on their supporters to advocate for the rules at lawmaker town halls during the Congressional recess.