In April, we reported that the Environmental Protection Agency (EPA) had taken steps to challenge California’s decades-old right to set its own air pollution rules, setting up a showdown between the federal government and the West Coast headquarters of the #Resistance.

Since then, the administration has prepared its plan to revoke California’s authority to regulate automobile greenhouse gas emissions, included its mandate for electric-car sales, and is gearing up for its release.

The proposal, expected to be released this week, amounts to a frontal assault on one of former President Barack Obama’s signature regulatory programs to curb emissions that contribute to climate change. It also sets up a high-stakes battle over California’s unique ability to combat air pollution and, if finalized, is sure to set off a protracted courtroom battle.

The proposed revamp would also put the brakes on federal rules to boost fuel efficiency into the next decade, said the people, who asked to not be identified discussing the proposals before they are public. Instead it would cap federal fuel economy requirements at the 2020 level, which under federal law must be at least a 35-mile-per-gallon fleet average, rather than letting them rise to roughly 50 mpg by 2025 as envisioned in the Obama plan, according to the people.

As part of the effort, the U.S. Environmental Protection Agency will propose revoking the Clean Air Act waiver granted to California that has allowed the state to regulate carbon emissions from vehicle tailpipes and force carmakers to sell a minimum number of electric vehicles in the state, the people said.

The National Highway Transportation Safety Administration (NHTSA) joins the EPA in this action, as the rationale for the revocation is enhanced safety.

The EPA and NHTSA revealed in a regulatory notice Friday that its upcoming proposal to reduce vehicle efficiency and emissions standards will be dubbed the “Safer and Affordable Fuel Efficient Vehicles Rule,” indicating that administration officials will likely argue that stricter standards would compromise safety.

Then-EPA head Scott Pruitt formally declared in April that the Obama plan to make emissions and efficiency standards stricter through 2026 is not appropriate. It was the first step toward potentially rolling the standards back.

The agencies are expected in the coming days to float a proposal with a handful of ideas, including various levels of looser rules through 2026 and freezing the standards in 2020 with no additional ramping up.

The response from green justice activists is fascinating, especially their newfound love of federalism.

At this point, the green justice warriors may be regretting their decision to target Scott Pruitt so viciously. The new acting head of the EPA seems to have taken the driver’s seat and is speeding along a road called Regulatory Rollback.