In an interview with Reuters in September, Pruitt said that he sees the Clean Power Plan as a form of federal "coercion and commandeering" of energy policy and that his state should have "sovereignty to make decisions for its own markets."
Of the 19 previous EPA administrators going back to 1970, Pruitt would easily be the most stridently anti-environment person to ever head the agency.
Word of Trump's pick immediately drew criticism from the left.
Sen. Brian Schatz, a Democrat representing Hawaii, also indicated he will oppose Pruitt to head the EPA.
And New York Attorney General Eric Schneiderman, a Democrat, said in a Wednesday statement that he stands ready "to use the full power" of his office to force the EPA to uphold national environmental laws. He called Pruitt "a dangerous and unqualified choice" for the agency.
Activist groups also decried Pruitt as Trump's EPA pick.
"Having Scott Pruitt in charge of the U.S. Environmental Protection Agency is like putting an arsonist in charge of fighting fires," Michael Brune, executive director of the Sierra Club, said in a release.
Greenpeace said through a spokesman that Pruitt had been "an enthusiastic shill for the fracking industry, and a reckless obstruction to the Clean Power Plan."
"By appointing Scott Pruitt as head of the Environmental Protection Agency, Trump is putting America at risk. Pruitt is a pure product of the oil and gas industry, installed in successive government posts to sell out his constituents at every turn," the Greenpeace spokesman said. "He will push this country far behind the rest of the world in the race for 21st century clean energy. With Scott Pruitt as head of the EPA, the people and the environment will be in the hands of a man who cares about neither."
The Obama administration finalized the Clean Power Plan in 2015 as a key part of meeting U.S. obligations under the Paris Climate Agreement. Trump vowed during his campaign to pull the United States out of the Paris deal, but since the election has said he will keep an "open mind."
— Reuters contributed to this report.