A total of 23 U.S. governors have said they will back California's leaders over their fight against the Trump administration's plan to loosen vehicle emissions standards.

The governors, almost all of whom are Democrats, said they support the idea of a national vehicle emissions standard, an idea that is currently threatened under the most recent Trump administration emissions proposal.

"[We] stand together in calling for one strong, national clean car standard and support preserving state authority to protect our residents from vehicle pollution," the governors wrote in a joint agreement.

The group, which they say represents 52 percent of the U.S. population and 57 percent of the economy, argues also in favor of a stringent pollution standard for cars.

"Strong vehicle standards protect our communities from unnecessary air pollution and fuel costs, and they address the largest source of carbon pollution in the United States," they wrote.

The promise by the governors follows a Trump administration attempt to halt more stringent standards put forth during the Obama administration.

The administration has argued that standards will increase automobile costs and keep older vehicles on the roads for more time.

The pledge was signed by the governors of Puerto Rico, Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Massachusetts, Minnesota, Montana, Nevada, New Jersey, New Mexico, New York, North Carolina, Oregon, Pennsylvania, Rhode Island, Vermont, Virginia, Washington and Wisconsin.

ADVERTISEMENT

“We will not compromise on our responsibility to protect the health of our communities, our climate, and the savings consumers stand to gain at the pump,” said the promise. “We will continue to pursue additional concrete actions to fulfill this duty and defend against any threats.”

The Environmental Protection Agency and National Highway Traffic Safety Administration submitted their proposed rule last August but it has not yet been finalized or signed by the White House.