A short-lived ceasefire over net neutrality is quickly coming to an end.

Silicon Valley is already rebelling against a plan by Republican FCC Chairman Ajit Pai that would cancel the government's net neutrality rules — and perhaps leave it to telecom giants like AT&T and Comcast to decide whether to adhere to open internet principles.

Under Pai's early blueprint, internet providers could be encouraged to commit in writing that they won't slow down or block internet traffic. If they break that promise, they could be penalized by another agency, the Federal Trade Commission, which can take action whenever companies deceive consumers, sources confirmed to Recode.

Pai's proposal hasn't officially been announced, and it obviously can change. If he pursues it, however, it would amount to a major break with his Democratic predecessor. During the Obama administration, the FCC wrote strong net neutrality protections into law, essentially subjecting the nation's telecom industry to utility-like regulation.

Many in Silicon Valley backed that approach — and now seem wary of Pai's plan to scrap it.

"I think in practice, it goes against everything we would want in strong net neutrality protections," said Evan Engstrom, the executive director of Engine, in an interview. The group works with startups on policy issues in San Francisco.

As a result, Engstrom said he expected a "similar level of engagement that we saw the last time around when we had to fight" — a vicious rhetorical war that drew even John Oliver into the fray. And he said the tech industry again would "do everything we can to rally the community and the public."