The Trump administration’s Environmental Protection Agency is planning to end California’s authority to set stricter automotive emissions standards in the state, The New York Times reports. The EPA is reportedly making the announcement during a private event in Washington on Wednesday while President Trump is fundraising in California. The order would revoke the state’s ability to set its own standards for tailpipe pollution—the largest source of greenhouse emissions in the United States. California is a major market in the automotive industry, making the state’s regulations a critical factor in automotive design, and effectively raising the bar in fuel efficiency standards across the country.

California is able to set its own tailpipe pollution rules because of a waiver granted to it under the 1970 Clean Air Act. When the landmark federal legislation went into place, California already had clean air legislation, so the law granted the state a waiver to set even stricter rules. Due to the state’s influence on the national auto market, 13 other states later adopted the same rules. Therefore, if the waiver is revoked, the auto industry could be forced to adhere to two sets of opposing standards. The Trump administration has championed the move despite automakers saying they do not want such drastic deregulation.