Trump to revoke Calif. emission rules

US President Donald Trump has moved to revoke California's right to set its own vehicle-emissions standards, drawing criticism from state officials who said such a move is an attack on states' right and a blow to the global warming fight.

"This will lead to more production because of this pricing and safety advantage, but also due to the fact that older, highly polluting cars, will be replaced by new, extremely environmentally friendly cars. There will be very little difference in emissions between the California Standard and the new US Standard, but the cars will be far safer and much less expensive," Trump wrote in a series of Twitter posts on Wednesday.

"Many more cars will be produced under the new and uniform standard, meaning significantly more JOBS, JOBS, JOBS! Automakers should seize this opportunity because without this alternative to California, you will be out of business," he added.

The Trump administration's decision to formally revoke California's car emissions rules authority is expected to be made on Thursday morning.

Andrew Wheeler, the head of the Environmental Protection Agency, and Elaine Chao, the transportation secretary, are expected to announce the formal abolition of the waiver at Environmental Protection Agency headquarters.

Trump made the announcement while on a trip in the Golden State. He arrived in California on Tuesday and made stops in Palo Alto, Beverly Hills and San Diego for campaign fundraising.

Some California lawmakers vowed to take legal action to block Trump's move.

"I'm confident we will prevail eventually. It will take years and years and years, more uncertainty, more anxiety. But California will prevail because we're leaders in this space," the Los Angeles Times quoted California Governor Gavin Newsom as saying during a news conference Wednesday.

California Air Resources Board Chair Mary Nichols said the measure will have dire consequences.

"Millions of people in California and other states that follow our standards will be breathing dirtier air. They will suffer from more pollution, more asthma cases, more hospitalizations, more premature deaths," Nichols said.

Former California governor Jerry Brown joined the fray. Responding to Trump's tweets, he said: "Your toxic tweets are insufferable, but your pillaging of our clean air is criminal."

California's authority to set its own tougher emissions standards was enabled by a waiver issued by Congress during the passage of the Clean Air Act in 1970.

California's tighter emissions standards are followed by 13 other states, which represents roughly a third of the national auto market, according to The New York Times.

If the Trump administration's move is upheld in court, it could permanently block states from regulating vehicle greenhouse gas pollution. If it were rejected by the Supreme Court, it would allow states to set their own emissions standards.

On Wednesday, Trump showed off a section of wall along the U.S. border with Mexico in a bid to illustrate his commitment to crack down on illegal border crossings.

The Republican president, who is on a three-day swing through the US West that has included a rally in New Mexico and a number of fundraisers in California, also used his trip to criticize the homelessness problem in Los Angeles and San Francisco, two heavily Democratic cities.

Trump traveled to Otay Mesa, a community in San Diego, to view the construction of a 30-foot-high (9-meter-high) steel and concrete barrier that is replacing existing border fencing. Trump said the wall goes deep into the ground, making it difficult to tunnel underneath, and is topped with heat-absorbing material to deter climbers.

Reuters contributed to this story.