Dive Brief:

• Protests and tough questioning are expected today in the U.S. Senate, as the Environment and Public Works Committee holds its confirmation for Oklahoma Attorney General Scott Pruitt (R), President-elect Donald Trump's nominee to head the Environmental Protection Agency.
• Environmentalists and clean energy advocates have decried Pruitt's nomination, saying his close ties with the fossil fuel industry, animosity toward the EPA's mission and rejection of mainstream climate science make him unfit for the job. 
• Pruitt's supporters, however, say his steadfast opposition to EPA policies throughout the Obama administration reflect a faith in federalism, rather than a rejection of the agency's mission to protect clean air and water. 

Dive Insight:

If preliminary comments are any indication, observers of the Senate Environment Committee today are in for a political firestorm. 

On one hand, environmental and clean energy groups have decried Scott Pruitt as the worst EPA nominee in history. Pruitt has a long record of cooperation with the fossil fuel industry on reducing pollution regulations, suing the Obama EPA 14 times, including over the Clean Power Plan, Mercury and Air Toxics Standards and the Cross-State Air Pollution Rules, among others.

Pruitt also rejects mainstream climate science, writing in a National Journal op-ed that "[s]cientists continue to disagree about the degree and extent of global warming and its connection to the actions of mankind."

Statements like that obfuscate the scientific consensus on warming. While some uncertainty always exists, the United Nation's Intergovernmental Panel on Climate Change — a group of top international climate scientists — holds that it is "extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century."

Pruitt's track record has put environmental groups on notice, with the Natural Resources Defense Council compiling the opposition of more than 170 green groups the week of the hearing. 

“President-elect Trump’s nominee to head the EPA, Oklahoma Attorney General Scott Pruitt, has actively worked against the mission of the agency he has been nominated to lead and he should be rejected by the Senate," the groups wrote to senators this week. 

But according to Pruitt's supporters, Oklahoma's top lawyer is more a friend of federalism—a concept of general government that shares power with states and provinces—and state's rights than an enemy of the EPA. 

"I think what a lot of people don't understand is a lot of the lawsuits he brought are driven entirely by his constitutional views," David Rivkin, a lawyer with the BakerHostetler firm who worked with Pruitt on the Clean Power Plan case, told the Christian Science Monitor this week. 

Instead of ​focusing on clean energy and climate change, Trump promised upon his appointment that Pruitt would “restore the EPA’s essential mission of keeping our air and water clean and safe."

Details of that strategy have been scant, but Pruitt would have a number of options to reshape the EPA's relationship with states and the power sector if he is confirmed.

One of the most lasting — and difficult — would be to attempt to rescind the EPA's endangerment finding on carbon dioxide, which classifies it as a pollutant under the Clean Air Act, compelling the EPA to regulate it. 

If the finding stands, EPA must issue some form of federal carbon regulation even if it repeals the Clean Power Plan, as Trump has promised. Pruitt's EPA could seek to reverse the endangerment finding, but it would have to prove in federal court that CO2 and other greenhouse gases should not be classified as pollutants. That would require years of litigation, likely reaching the Supreme Court. 

But the man many call "the Possum" may be up for the challenge. Pruitt joined 14 other attorneys general in a 2012 court challenge to the endangerment finding, eventually thrown out by the D.C. Circuit Court. Reversing that decision would be a tough task, lawyers told E&E news, but Trump appointees to the bench could tip the scales later in the administration.

Pruitt's hearing begins at 10 a.m. EST and can be streamed at the Senate Environment and Public Works website.