More than 270 employees of the Environmental Protection Agency signed a letter on Monday denouncing what they described as the Trump administration’s efforts to politicize, dismantle and sideline the main federal agency tasked with protecting the environment and public health.

The letter to President Trump’s E.P.A. administrator, Lee Zeldin, was a remarkable rebuke of the agency’s political leadership. It followed a similar missive sent this month by more than 60 employees of the National Institutes of Health, who criticized orders they saw as illegal and unethical.

“E.P.A. employees join in solidarity with employees across the federal government in opposing this administration’s policies, including those that undermine the E.P.A. mission of protecting human health and the environment,” the E.P.A. workers wrote.

The four-page document outlined five overarching concerns with the Trump administration’s approach to the E.P.A. The top complaint was that decisions had been made based on a political agenda, not on science and the law.

Recent E.P.A. news releases and newsletters have parroted some of Mr. Trump’s rhetoric on the environment, the letter said. For example, these materials have praised coal as “beautiful” and “clean.” Coal is the dirtiest of the fossil fuels and is a significant source of greenhouse gases. Statements from the E.P.A. have also routinely referred to climate grants issued under the Biden administration as a “green slush fund,” when there has been no evidence they were used for illicit purposes.

“I’ve never seen this kind of partisanship, even in the first Trump administration,” said Justin Chen, an environmental engineer in the E.P.A.’s Dallas-based Region 6 office who signed the letter. Mr. Chen emphasized that he was speaking in his personal capacity and not on behalf of his E.P.A. office.