Two former Republican administrators of the Environmental Protection Agency on Tuesday endorsed Hillary Clinton, becoming the latest in a series of one-time GOP government officials to back the Democratic presidential nominee over Donald Trump.

In a joint statement, William D. Ruckelshaus and William K. Reilly say that Trump has showed “a profound ignorance of science and of the public health issues embodied in our environmental laws” and that Clinton is “committed to reasonable, science-based policy.”

Ruckelshaus was the first administrator of the EPA, serving under President Richard Nixon. He returned to the same position during the presidency of Ronald Reagan. Reilly was the EPA administrator under President George H.W. Bush.

In recent weeks, several other former federal officials serving under Republican presidents have stepped forward to back Clinton, a former secretary of state.  In addition, dozens of national security officials who served in GOP administrations signed a letter saying that Trump is “not qualified” to be president.

In their statement, Ruckelshaus and Reilly say that Republicans have a long history of environmental stewardship, noting that Nixon created the EPA, and argue that Trump, a real estate mogul, “threatens to destroy that legacy.”

The former administrators take particular exception to Trump’s stand on climate change, which he has characterized as a hoax. They say climate change is “the singular health and environmental threat to the world today” and praise the Paris agreement adopted in December by nearly 200 nations.

“To back away now, as Trump wants to do, would set the world back decades — years we could never recover,” the statement from Ruckelshaus and Reilly says. “The young people in this country deserve far better than that as our legacy.”