President Trump.

U.S. President Donald Trump on Wednesday said he is revoking California’s ability to independently set its own car emissions standards, which have been more stringent than most of the country.

California was granted a waiver to set car emission standards that were stricter than federal regulations in 2013, under the administration of President Barack Obama.

Trump’s move marks the latest clash between the deeply Democratic state and his administration over climate issues.

California is the largest U.S. state by population and is particularly dominant when it comes to new car sales, giving the state government tremendous influence over policy.

In a tweet, Trump said there would be very little difference in emissions between the California Standard and the new U.S. Standard, but the cars would be far safer and much less expensive.

The Governor of California, Gavin Newsom, and Attorney- General Xavier Becerra, would respond to the development during a press conference on Wednesday.

The move comes after the U.S. Justice Department reportedly opened an anti-trust investigation into four automakers that negotiated with California to set mileage standards.