By Juliet Eilperin and Dino Grandoni 
September 24, 2019 at 11:14 a.m. EDT

Trump administration officials threatened this week to withhold federal highway funds from California, arguing that it had failed to show what steps it is taking to improve its air quality. The move by the Environmental Protection Agency escalates the fierce battle between President Trump and the left-leaning state, and could put billions in federal funds in jeopardy.

In a predated letter sent late Monday to the California Air Resources Board, EPA Administrator Andrew Wheeler suggested that the state “has failed to carry out its most basic tasks under the Clean Air Act,” and needs to either update its plans to tackle air pollution or risk losing federal highway funds.

At stake, the EPA said, are billions of dollars in federal highway funding every year. Federal officials have the right to halt that money if they determine a state is not taking sufficient steps to show how it aims to cut air pollution such as soot or smog-forming ozone.ADVERTISING

In the letter, Wheeler notes that 34 million Californians live in areas that don’t meet federal National Ambient Air Quality Standards, more than twice as many residents than any other state. California has more than 130 “state implementation plans,” which serve as blueprints for how California would tackle these pollutants, awaiting federal approval.

“California has the worst air quality in the United States,” he wrote, adding that many of its plans “are inactive and appear to have fundamental issues” that would keep them from getting approved.

The decision to invoke a rarely used federal punishment represents the latest salvo in the Trump administration’s feud with California over environmental and other policy issues. Just last week, the EPA joined the Transportation Department in revoking California’s right to set stricter pollution limits on cars and light trucks.

“I’ve never seen a letter like this before,” said Janet McCabe, former acting assistant administrator for the EPA’s Office of Air and Radiation under President Barack Obama. “It’s ironic that EPA is taking California to task for not solving the air quality problem when for decades the state has been moving forward with the most aggressive clear air rules and programs in the nation.”

She added: “That’s clearly threatening language in there.”

California officials have repeatedly argued that they have sought to impose stricter limits on greenhouse gas emissions from vehicles as part of a broader effort to tackle smog in their state. The vehicle standards the Trump administration is blocking, CARB chairwoman Mary Nichols said last week, “are necessary to protect the public health standards and welfare.”

Nichols could not immediately be reached for comment Tuesday.

Bill Becker, president of Becker Environmental Consulting, said in a phone interview that it did not make sense for the administration to punish California for failing to address air pollution in the state when it was simultaneously blocking its efforts to cut down on these emissions.

“Isn’t it ironic that EPA is taking away some of the important regulatory tools for meeting the federal health-based standards, and then sanctioning California?” Becker said. “It’s like the kid killing his parents, and then pleading for mercy because he’s an orphan.”

The Los Angeles area and other parts of the mountainous state have long struggled with smog. Trapped by mountains on three sides, the car-clogged Southern California region forms a basin in which dirty air pools. Smog levels rose so high there in the middle of the 20th century that Congress gave California a special status under the Clean Air Act to set its own pollution standards.

A senior EPA official, speaking to reporters Tuesday, said California’s pollution situation was “unique” and required the aggressive step. But about three dozen other states also had counties that failed to meet air standards for six different pollutants, as of the end of August.