In its rush to roll back the most significant climate policy enacted by President Barack Obama — mileage standards designed to reduce pollution from cars — the Trump administration ignored warnings that its new rule has serious flaws, according to documents shared with The Washington Post.

The behind-the-scenes skirmish in late March between career employees and Trump appointees at the Environmental Protection Agency highlights the extent to which Trump officials are racing to reverse environmental policies by the end of the president’s first term.

Even as the coronavirus outbreak has hampered many government operations, the administration is pressing ahead with the rollback of a bedrock environmental law governing federal permits and working to open more public lands to oil and gas drilling. In recent weeks, the EPA has opted not to set stricter national air quality standards, and it is poised to defy a court order requiring that it limit a chemical found in drinking water that has been linked to neurological damage in babies. The agency soon plans to finalize a change to the Clean Water Act that would restrict the ability of states, tribes and the public to block federal approval for pipelines and some other energy-related projects.

The documents — obtained by Sen. Thomas R. Carper (Del.), the top Democrat on the Environment and Public Works Committee — include an exchange between two agencies that has not been entered into the public record as required under the Clean Air Act.

Details about objections from EPA staff could create legal problems for the administration’s Safer Affordable Fuel-Efficient (SAFE) Vehicles rule, which requires U.S. cars, pickup trucks and SUVs to improve average fuel efficiency by 1.5 percent each year between model years 2021 and 2026. It replaces Obama-era standards that would have improved the auto fleet’s average mileage by 5 percent a year over the same period.

“In the rush to finalize this rule — and in the middle of a pandemic, no less — they broke just about every rule in the book,” said Carper, who on Monday asked the EPA inspector general to investigate. “The result is a policy that fails to protect public health, fails to save money, fails to result in safer vehicles and will, ultimately and undoubtedly, fail in court.”

In his letter, Carper argued the EPA violated federal rules by failing to enter all relevant documents into the public record, changing the rule after it was signed and not meeting its obligation to write its part of the mileage rule.

Jeff Lagda, a spokesman for the EPA inspector general, said in an email that the office is reviewing Carper’s letter.

In an email Tuesday, EPA spokeswoman Corry Schiermeyer said the approach the agency followed is in line with other joint rulemakings it has undertaken, including in past administrations.

She said written, deliberative discussions between agencies on a rule about how to draft a notice or respond to comments during an interagency review typically are not included in the public record. “This approach is compatible with the docketing requirements of the Clean Air Act,” Schiermeyer wrote.

In addition, she said the final rule unveiled in March was the result of a long and cooperative effort between the EPA and the Transportation Department.

“It is the result of a collaborative process between EPA and [National Highway Traffic Safety Administration] and takes into account over 750,000 comments from a diverse group of stakeholders,” she said.

For months, Transportation Secretary Elaine Chao and EPA Administrator Andrew Wheeler have insisted that their staffs collaborated closely to weaken national greenhouse gas standards for cars and light trucks that were finalized just days before Obama left office.

Speaking at a joint appearance at EPA headquarters in September, Chao declared, “Our team of experts have been jointly working together, conducting a long, thoughtful and detailed review of these rules.”

Wheeler echoed her remarks, thanking the secretary and her staff “for the professionalism . . . in everything that we’ve done together.”

The documents, however, reveal that EPA staff were sidelined as they warned that the revised standards had several defects.

Commenting on the preamble’s assertion that the government’s “action will result in reductions in climate change-related impacts and most air pollutants compared to the absence of regulation,” EPA staffers wrote in an internal document in February that “this is not correct” from the agency’s perspective.

“The action revising the [greenhouse gas] standards will result in increased climate impacts and air pollution emissions compared to the existing standards,” agency staff wrote in the margins.

In a Jan. 30 presentation to the head of the EPA’s Office of Air and Radiation, according to a document obtained by The Post, staffers stated that the rule submitted to the White House Office of Management and Budget did not reflect their work.

It noted that the EPA had not seen about two-thirds of the 1,000-page document that Transportation Department staffers had submitted to the White House to justify the change in the mileage standards.

Four days before the rule was signed by Wheeler, the top EPA official in charge of setting fuel economy standards wrote an email saying Transportation Department officials had not addressed more than 250 comments by EPA experts.

“Factually inaccurate text has still not been corrected in numerous places,” Bill Charmley, who heads the assessment and standards division at EPA’s National Vehicle and Fuel Emissions Laboratory in Ann Arbor, Mich., wrote in a March 26 email to his superiors.

Charmley warned that incorrect information in the rule would make it vulnerable to legal challenges. He did not respond to a request for comment.

The detailed comments Charmley referred to were made on documents the Transportation Department submitted to the White House for review earlier this year, which normally would be entered into the record under a requirement under the Clean Air Act.

Kevin Minoli, who held the highest-ranking career attorney position in the EPA under the Trump administration before joining the firm Alston & Bird in late 2018, said the fact that top officials there may have ignored the advice of career staff does not necessarily undermine the basis for the new mileage standards. Political appointees have the authority to direct the agency’s actions, and Wheeler’s signature on the rule makes it an official agency action.

But it creates risks for the agency, Minoli said. “The career employees on EPA’s mobile source team are the most experienced technical and legal experts in their field, and the choice not to rely on them substantially increases the chance that the regulation will be vulnerable to a substantive challenge,” Minoli said in an email. “But it does not, in and of itself, constitute grounds for a court to overturn the rule.”

Mike Danylak, a spokesman for Senate Environment and Public Works Committee Chairman John Barrasso (R-Wyo.), said in an email that the senator supports the new mileage rule “and the commonsense standards it established to protect America’s air, while preserving consumers’ vehicle choice.”

Barrasso looks forward to hearing more on the EPA’s work Wednesday, when Wheeler is set to testify before the committee, Danylak said.

Public records show that Wheeler made significant changes to the rule after he signed it, before it was published in the Federal Register, which is unusual. The rule Wheeler signed on March 30 has multiple errors, including one table on new mileage standards that says “passenger cars” when it should have said “light trucks” and an assertion that cars would become nearly 5 percent less carbon-intensive between model years 2020 and 2021.

Schiermeyer, the EPA spokeswoman, said such changes are “commonly used by federal agencies to correct errors in notices prior to publication in the Federal Register,” and that Wheeler’s tweaks corrected “inadvertent errors in the pre-publication version of the preamble and regulatory text.”

Jeff Alson, a former senior engineer at the EPA’s vehicles lab who retired in 2018 after four decades, said the factual errors show how rushed the process was.

“It’s really unbelievable and unprecedented to make an error like that,” said Alson, adding that the charts matter because they lay out the legal obligations of automobile manufacturers. “The lawyers should have said to the engineers, ‘You got those tables right, right?’ ”

Peter Zalzal, lead attorney for the Environmental Defense Fund, said in an interview that making major changes between the signed and published rule requires “technical correction notices. This is really highly irregular.”

The EDF notified the agency on May 8 that it plans to sue the EPA if it does not publish in the federal rulemaking docket all interagency review materials, including comments its staff made on the Transportation Department proposal sent to the White House. It is also gearing up to challenge the administration’s SAFE rule, in concert with other environmental groups and some Democratic attorneys general.

Zalzal said he remains optimistic that opponents will be able to overturn the new mileage standards in court.

“The agency here has adopted a rule that, by their own analysis and all scenarios, hurts the public and runs contrary to the agency’s mandate,” he said. “It is increasing fuel use, it is increasing pollution and it is hurting the public.”

The ongoing fight over federal fuel efficiency requirements has unfolded in contentious fits and starts during President Trump’s first term. In 2018, the Trump administration first proposed weakening the 2009 requirements put in place by the Obama administration, which had argued that stricter standards would improve public health, mitigate climate change and save consumers money without compromising safety.

In contrast, the Trump administration has insisted that forcing automakers to increase the fuel economy of their fleets would make new vehicles more expensive and encourage people to drive older, less-safe cars and trucks. It has also cited arguments from the auto industry that the market has changed since the Obama-era standards were developed — namely, that low fuel prices have made buyers gravitate toward SUVs and pickup trucks in far larger numbers than smaller, more efficient cars.

The rule finalized this spring estimates there will be fewer accident-related deaths over the lifetime of vehicles sold between 2021 and 2029 as more people trade older cars for newer, safer ones. The government’s own estimates, however, say more Americans will die as a result of increased air pollution during that period than if the existing standards remained in place.