WASHINGTON — President Trump on Wednesday posted on Twitter an aggressive defense of his unprecedented move to abolish California’s legal authority to set its own standards on climate-warming automobile emissions.
Mr. Trump was in Los Angeles for a fund-raiser when he wrote in defense of a move that California officials and environmental advocates have assailed as an illegal attack on states’ rights and on a major policy designed to fight climate change.
“The Trump administration is revoking California’s Federal Waiver on emissions in order to produce far less expensive cars for the consumer, while at the same time making the cars substantially SAFER,” Mr. Trump wrote in the first of several posts. He said the change would lead to increased auto production and claimed that the newer cars would be “extremely environmentally friendly.”
The Trump administration is expected later on Wednesday to formally revoke California’s authority to set auto emissions rules that are stricter than federal standards, taking a major step forward in the administration’s wide-ranging attack on efforts to fight climate change.
The formal abolishment of one of California’s signature environmental policies — tailpipe pollution is the largest source of greenhouse gas emissions in the United States — is expected to be announced Wednesday afternoon at the Washington headquarters of the Environmental Protection Agency, according to two people familiar with the matter.
A revocation of the California waiver would have national significance. Thirteen other states follow California’s tighter standards, together representing roughly a third of the national auto market.
Legal experts said that if Mr. Trump’s move was ultimately held up by the Supreme Court, it could permanently block states from regulating vehicle greenhouse gas pollution. If it was rejected by the Supreme Court, it would allow states to set separate tailpipe pollution standards from those set by the federal government.
The outcome could split the United States auto market, with some states adhering to stricter pollution standards than others. For automakers, that would be a nightmare.
The move has been widely expected since last summer, when the Trump administration unveiled its draft plan to roll back the strict federal fuel economy standards put in place by the Obama administration. That draft Trump rule also included a plan to revoke the state’s legal waiver — granted to California under the 1970 Clean Air Act — allowing it to set tougher state-level standards than those put forth by the federal government.
The administration’s plans have been further complicated because major automakers have told the White House that they do not want such an aggressive rollback. In July, four automakers formalized their opposition to Mr. Trump’s plans by signing a deal with California to comply with tighter emissions standards if the broader rollback goes through.
Mr. Trump, who was blindsided and angered by that announcement, according to two people familiar with the matter, wanted to press forward with a policy that would punish California.
The Obama-era tailpipe pollution rules that the administration hopes to weaken would require automakers to build vehicles that achieve an average fuel economy of 54.5 miles per gallon by 2025, cutting about six billion tons of carbon dioxide pollution over the lifetimes of those vehicles. The proposed Trump rule would lower the requirement to about 37 miles per gallon, allowing for most of that pollution to be emitted.
White House officials have been eager to move quickly to revoke California’s authority to set its own standards because they want the opportunity to defend the effort in the Supreme Court before the end of Mr. Trump’s first term. The thinking goes that if a Democrat were to be elected president in 2020, the federal government would be unlikely to defend revocation of the waiver in the high court.
California’s special right to set its own tailpipe pollution rules dates to the 1970 Clean Air Act, the landmark federal legislation designed to fight air pollution nationwide. The law granted California the right to receive federal waivers to set stricter rules of its own because the state already had clean air legislation in place before it passed.
Over the decades, California requested and received numerous federal waivers to set tighter state-level standards on the tailpipe pollutants that cause smog and respiratory problems, though the federal government didn’t always grant them.
The waiver in effect now was crafted in the wake of the 2008 financial crisis, when the nation’s automakers were financially teetering. It was part of a deal struck by President Barack Obama to toughen emissions standards nationwide while aligning California’s rules with federal regulations. It was designed to remain in effect until 2025.
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