The Trump administration will reportedly seek to revoke California’s authority to regulate automotive emissions, including the state’s mandate for EV sales.

According to Bloomberg, which cites three people familiar with the Trump administration’s plan, the proposal is expected to be released this week. This will be a frontal assault on one of the previous administration’s signature policies to cut down greenhouse gas emissions.

The plan is also likely to set up a high-stakes battle over California’s unique position to regulate emissions. If successful, the plan is also expected to set off a long courtroom battle.

The proposed regulations revamp will also stop the current federal rules aiming to boost fuel efficiency into the next decade. Instead, Trump’s plan will cap federal fuel economy requirements at the 2020 level, meaning at least 35mpg fleet average rather than roughly 50mpg by 2025 as envisioned in the plan left behind by the previous administration.

The effort will include EPA proposing to revoke the Clean Air Act waiver granted to California, which has allowed the state to regulate vehicle carbon emissions and force manufacturers to sell electric vehicles within the state in higher numbers.

NHTSA will likely assert that California can no longer impose its own greenhouse gas emissions from autos under the 1975 law that established the first federal fuel-efficiency requirements.

Once the proposal is formally unveiled, the public will have a chance to weigh in, with the feedback used to develop a final rule that could be implemented as soon as the end of the year.

While the proposal will include other options, the Trump administration is expected to focus on the dramatic overhaul that includes revoking California’s unique authority, according to the same sources.