The National Climate Assessment, America's premier contribution to climate knowledge, stands out for many reasons. Hundreds of scientists across the federal government and academia join forces to compile the best insights available on climate change. The results, released just twice a decade or so, shape years of government decisions.

Now, as the clock runs down on President Donald Trump's time in office, the climate assessment has gained a new distinction: It is one of the few major U.S. climate initiatives that his administration tried, yet largely failed, to undermine.

How the Trump administration attempted to put its mark on the report, and why those efforts stumbled, demonstrates the resilience of federal climate science despite Trump's haphazard efforts to impede it. This article is based on interviews with nearly a dozen current and former government officials and others familiar with the process.

In November, the administration removed the person responsible for the next edition of the report and replaced him with someone who has downplayed climate science. But the efforts started back in 2018, when officials pushed out a top official and leaned on scientists to soften their conclusions — the scientists refused — and then later tried to bury the report, which did not work either.

"Thank God they didn't know how to run a government," said Thomas Armstrong, who during the Obama administration led the U.S. Global Change Research Program, which produces the assessment. "It could have been a lot worse."

What makes the failure to impede the climate assessment remarkable is that Trump made it a top priority to undercut efforts to address climate change. And on most fronts, he succeeded, reversing scores of environmental rules, relaxing restrictions on air pollution, and opening new land to oil and gas drilling.

The national assessment enjoys unique prominence, pulling together the work of scientists across the federal government. The law requires a new one every four years.

For Trump, who has called climate change a hoax, the assessment posed a particular challenge. Trying to politicize or dismiss climate science is one thing when the warnings come from Democrats or academics. But this report comes from his administration's own people.

The first evidence of this tension came in the summer of 2018 as federal scientists were finishing the fourth National Climate Assessment. The report warned that climate change would endanger public safety and economic growth. And it said that cutting emissions "can substantially reduce climate-related risks," in contradiction of the Trump administration's efforts to reverse such cuts.

Stuart Levenbach, a political appointee who was then chief of staff at the National Oceanic and Atmospheric Administration, which oversees the assessment, pushed the scientists preparing the document to tone down the findings in their summary.

Levenbach, who is now a senior adviser at the White House National Economic Council, said that he simply wanted the summary to be more clear about the assumptions it relied upon about future emissions.

The career staff refused to make those changes. The administration then released the document on the day after Thanksgiving, in an apparent attempt to minimize attention. That approach backfired: Many news organizations interpreted the timing as evidence of the report's importance, giving it prominent coverage.

Once the climate assessment had been issued, the White House Office of Science and Technology Policy, which oversees the Global Change Research Program, decided it was best to stop talking about it at all, according to people involved.

The office put a halt to any activities that might draw attention to the assessment. Additional reports, meant as periodic updates, stopped getting released. Plans for the authors to meet with local officials in places threatened by climate change and talk about their findings were shelved.

The White House spokesperson called the descriptions "false."

Urging staff not to talk about their work succeeded in keeping it off Trump's radar, at least for a time.

Another White House decision would also help keep the climate assessment out of the news: The head of the science office, Kelvin Droegemeier, delayed the release of the next installment to 2023 from 2022, according to people familiar with his decision.

The Global Change Research Program's website now says the "anticipated delivery" for the next report is 2023.

But that delay had a silver lining, said Jesse Keenan, a Tulane professor who edited two chapters for the previous assessment. Each report relies on the scientific research it draws on — and under the Trump administration, new climate research has slowed, Keenan said.

Delaying the release of the next assessment "is going to give us an opportunity to catch our breath and get some output in the next year" from federal scientists, he said.

In November, the White House removed the head of the Global Change Research Program, climate scientist Michael Kuperberg. He was replaced by David Legates, a Trump appointee at the NOAA who previously worked closely with groups that deny climate change.

A second NOAA political official, Ryan Maue, who has criticized climate scientists for what he has called unnecessarily dire predictions, was moved to a role in the White House that gave him authority over the climate program.

The appointments produced anxiety among scientists, who worried it represented an effort by the administration to learn from its failure to change the previous assessment — by installing loyalists.