Story highlights They charged that Donald Trump doesn't believe in climate change

The latest Republicans to cross party lines to back Hillary Clinton

(CNN) Two former administrators of the Environmental Protection Agency under Republican presidents endorsed Hillary Clinton on Tuesday, citing her plan to tackle climate change and Donald Trump's "profound ignorance of science."

William D. Ruckelshaus, who was the first EPA administrator under President Richard Nixon and then again the fifth under President Ronald Reagan, and William K. Reilly, the administrator under President George H. W. Bush, said in a joint statement that while Republicans have a history of protecting the environment, Trump "threatens to destroy that legacy of respect for the environment and protection of public health."

"That Trump would call climate change a hoax -- the singular health and environmental threat to the world today -- flies in the face of overwhelming international science," the duo said.

Trump tweeted in 2012, that "The concept of global warming was created by and for the Chinese in order to make U.S. manufacturing non-competitive."

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