WASHINGTON (Reuters) - Senior U.S. government officials held talks in recent weeks with California’s Air Resources Board (CARB) to discuss the goal of maintaining one set of national requirements for automakers, a move that will determine the fate of vehicle emissions rules.

Consumers purchase gasoline at a gas station as a plane approaches to land at the airport in San Diego, California October 8, 2012. REUTERS/Mike Blake

The Dec. 15 meeting held in California included William Wehrum, head of the Environmental Protection Agency’s Office of Air and Radiation, National Highway Traffic Safety Administration (NHTSA) deputy chief Heidi King, and Mike Catanzaro, a senior White House aide on environment and energy issues, a spokesman for CARB confirmed on Monday.

Automakers want the White House and California to reach agreement on revisions because a legal battle over the rules could result in lengthy uncertainly for the industry. They also want changes in the rules to address lower gas prices and a shift in U.S. consumer preferences to larger, less fuel-efficient vehicles.

“We’ve had productive conversations under way with CARB and I would hope those conversations continue to be productive,” Wehrum said in an interview Friday at EPA headquarters. “I think a shared goal is to maintain one national program.”

In 2011, California’s air emissions regulator and the Obama administration reached an agreement with major automakers to nearly double average fleetwide fuel efficiency to more than 50 miles per gallon by 2025, but included a “midterm review” to determine by April 2018 whether the final requirements were feasible.

California, joined by nearly a dozen other states, could seek to enforce its own current stricter emissions rules even if the Trump administration softens the 2022-2025 requirements.

The Obama administration announced it had completed the midterm review in its final days in January 2017 without making changes.

In a move widely seen as a preamble to loosening fuel standards, U.S. President Donald Trump announced in March he was revisiting the 2025 requirements. “The assault on the American auto industry is over,” Trump said. “We are going to ensure that any regulations we have protect and defend your jobs, your factories.”

Wehrum said if there was a “good solid technical basis” for revising the requirements, he hoped California would agree, adding the talks have been “very collegial and collaborative,” including that the December 15 meetings with California officials lasted for a couple of hours. He emphasized EPA has made no decisions on whether the requirements should be lowered.

CARB spokesman Stanley Young confirmed the discussion but declined to elaborate. Catanzaro did not respond to a request for comment.

NHTSA has said it plans to issue its proposed changes, if any, for the 2022-25 model years by March 30. NHTSA’s King declined to comment Monday on the status of the agency’s review or California talks. Regulators could also propose changes for 2021.

In June, New York state’s attorney general and 12 other top state law officials said they would mount a court challenge to any effort to roll back vehicle fuel rules.

Gloria Bergquist, a spokeswoman for the Alliance of Automobile Manufacturers, a trade group representing General Motors Co , Toyota Motor Corp, Volkswagen AG VOWG_p.DE and others, said the companies "fully support conversations between all the relevant parties."