President Trump is expected Wednesday to revoke a decades-old rule that empowers California to set tougher car emissions standards than those required by the federal government — putting the state and the administration on a path to years of fighting in court.

The move, which has been in the works for much of the last three years, would overturn the foundation for California’s role as an environmental leader in reducing greenhouse gas emissions and improving air quality. By revoking a special waiver the state has relied on for years to set its own standards, the administration will be saying that no state can impose more ambitious pollution controls than those adopted by the federal government.