WASHINGTON (Reuters) - The United Auto Workers (UAW) will tell Congress on Thursday the union opposes the Trump administration’s proposal to freeze fuel efficiency requirements at 2020 levels through 2026, according to written testimony.

UAW Legislative Director Josh Nassar will tell two subcommittees of the U.S. House Energy and Commerce Committee that the union shares automakers’ concerns that the proposal “could lead to protracted litigation and uncertainty in the industry that will limit growth.”

The union represents workers at General Motors Co, Ford Motor Co and Fiat Chrysler Automobiles NV.

Deputy National Highway Traffic Safety Administrator (NHTSA) Heidi King told the U.S. Senate Commerce Committee on Wednesday that existing fuel efficiency standards have hiked the cost of new vehicles and may “discourage consumers from replacing their older car with a newer car that is safer, cleaner and more fuel efficient.”

She will raise concerns before the House panel Thursday that the United States is “facing an affordability crisis in the new car market,” according to her testimony seen by Reuters.

King said NHTSA and the Environmental Protection Administration are reviewing more than 650,000 comments. King and Bill Wehrum, the EPA’s assistant administrator for air and radiation, will testify on Thursday at the House hearing. The agencies are working to finalize the rule “as soon as possible,” according to Wehrum’s written testimony.

The “preferred alternative will prevent thousands of on-road fatalities and injuries” compared to the Obama-era standards “as more people can afford safer, new cars,” his testimony said. Environmentalists and California strongly disagree with that analysis.

California and 17 other states have vowed to sue to block any freeze of the emissions requirements.

The Trump administration’s “preferred alternative” would increase U.S. oil consumption by about 500,000 barrels a day by the 2030s but reduce automakers’ regulatory costs by more than $300 billion, the two agencies contend.

Mary Nichols, who heads the California Air Resources Board, will also testify Thursday on a separate panel. The Trump proposal will cost Americans millions more in fuel costs, kill jobs, add smog, undermine the auto industry and worsen the climate crisis, according to her written testimony.

She said the White House ended discussions that automakers have urged be restarted.

“We have been open to accommodations that would adjust compliance timing and flexibility, that would create new paths to promote innovative technologies and zero emission vehicles, and that would benefit the public,” she said, adding her agency estimates “the net cost of the federal rollback nationally at $168 billion.”

Louisiana Attorney General Jeffrey Landry will tell the House panel Thursday that “California should not be able to effectively dictate fuel economy standards, tailpipe emission requirements, and mandates for zero emission vehicles.”

“California has circumvented Congress and used its size to create a de facto national fuel efficiency framework,” according to his testimony.

Earlier this month, 17 major automakers including GM, Volkswagen AG and Toyota Motor Corp, urged the White House to resume talks with California to avoid a lengthy legal battle. Automakers backed a compromise, warning that the lack of a deal could lead to “an extended period of litigation and instability.”

The carmakers urged a compromise “midway” between the Obama-era standards that require annual decreases of about 5% in emissions and the Trump administration’s proposal.

Energy company BP Plc weighed into the debate urging the EPA and NHTSA to work with automakers and others to find a path that “continues the impressive trajectory of efficiency improvements” already seen in engines, as they balance vehicle safety and affordability. The June 13 letter, seen by Reuters on Wednesday, was sent to Administrator Andrew Wheeler.

Nassar will say that the UAW urged California, the White House and others “to develop balanced regulations that are good for the environment, American workers, U.S. manufacturing, and the economy.”

David Friedman, a former deputy NHTSA administrator under President Barack Obama and a vice president at Consumers Reports, will testify on Thursday that “automakers have the technology to make better, safer, more efficient vehicles, and federal agencies should strengthen the current standards to save Americans’ money.”