Oklahoma Attorney General Scott Pruitt answered questions in a heated EPA confirmation hearing Wednesday on Capitol Hill.
President-elect Donald Trump tapped Pruitt to head the EPA last month, sparking controversy among environmental groups.
Pruitt has sued the EPA more than a dozen times.
The fireworks went off at climate change.
"My personal opinion is immaterial [on climate change],” Pruitt told the panel.
"Really? You're going to be the head of the agency to protect the environment, and your personal feelings about whether climate change is caused by human activity and carbon emission is immaterial?” asked Sen. Bernie Sanders (I-VT).
"Senator, I've acknowledged to you human activity impacts..." Pruitt responded.
"Impacts? The scientific community doesn't say it impacts. They say it is the cause of climate change. We have to transform our energy system,” Sanders said.
Pruitt has previously cast doubts on climate change and is suing the EPA right now over President Obama’s Clean Power Plan, which was meant to reduce greenhouse gas emissions.
Senators grilled Pruitt on the air quality in Oklahoma.
"Did you even file one lawsuit, one lawsuit on what happened to those kids to reduce the air pollution in your state to help them have a healthy life?” asked Sen. Cory Booker (D-N.J.).
“The state has to have an interest before you bring those cases, as you know. You can't just bring a lawsuit if you don't have standing if there's not been some injury to the state of Oklahoma,” Pruitt replied.
And, there was more criticism over Pruitt’s ties to big oil.
“Your state is seeing a record number of earthquakes. You acknowledge you're concerned. If that's the kind of EPA administrator you will be, you're not going to get my vote,” Sanders said.
But, Republicans on the committee said they were hopeful Pruitt could lead the EPA in a new direction.
And, back at home, there was more support from leaders like former Oklahoma Attorney General Mike Turpen, a democrat.
“General Pruitt does believe the EPA has overreached with their rule making. He believes they ought to follow the dictates of Congress. I think one of the best things Trump has done is pick Scott Pruitt,” Turpen said.
Regarding his slew of lawsuits against the EPA, Pruitt told the committee he’d be willing to recuse himself going forward.
Pruitt is expected to be confirmed.