It was Trump's latest step to fill out his all-important cabinet in the weeks before the maverick billionaire takes the helm of the planet's largest economy, with observers worldwide on tenterhooks over how he will conduct policy on climate, national security, trade and immigration.
The Republican's victory shocked the US establishment and alarmed many who are waiting to see if the political novice follows through on a slew of threats to tear up free trade agreements, abandon treaties and punish American companies that offshore jobs.
He also will reportedly announce retired general John Kelly to run the Department of Homeland Security. Kelly would be the third general named to Trump's inner circle, amid some concern that Trump is surrounding himself with military figures in civilian posts.
But Trump's choice of Oklahoma Attorney General Pruitt as EPA administrator has outraged many Trump opponents who fear for the fate of President Barack Obama's efforts to combat climate change.
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Pruitt "will reverse this trend and restore the EPA's essential mission of keeping our air and our water clean and safe."
The EPA chief has a strong impact on US actions to combat climate change: the agency both determines what international commitments the country is able to make, and implements them.
Opponents scoffed at Trump's suggestion that Pruitt will be a capable steward of the environment, pointing out he has spent much of his time battling the very agency he is now tapped to lead
"There is nothing good about this," Michael Burger, executive director of the Sabin Center for Climate Change Law at Columbia Law School, told AFP.
"Pruitt is a known conspirator with the fossil fuel industry and I mean that in a literal sense," he said, pointing to the Oklahoman's 2014 efforts with oil companies to battle EPA regulations.
Ken Kimmell, president of the Union of Concerned Scientists, described Pruitt as "someone who is on the outer extreme edge, and putting him in charge of EPA could really have devastating consequences" as Pruitt will likely seek to dismantle Obama's Clean Power Plan.