Environmental Protection Agency Administrator Scott Pruitt said in his first testimony before Congress on Thursday that he plans to replace the Obama-era Clean Power Plan, instead of just killing it outright.

“We are going to be introducing a replacement rule, too,” Pruitt said, in response to a question from Rep. Raul Ruiz, D-Calif., during a House Energy and Commerce Committee hearing.

But Pruitt also criticized the 2009 agency rule known as the endangerment finding, which forces the EPA to regulate carbon dioxide and other greenhouse gases. He said the process to establish the endangerment finding was "accelerated and "short-shrifted."

And he confirmed he will start as soon as next month a so-called “red team, blue team” exercise to allow experts to debate the science of climate change, which critics see as an attempt to undermine the consensus that human emissions of carbon are making global warming worse.

Pruitt’s comments were in his first hour of testimony Thursday morning before a subcommittee of the Energy and Commerce Committee. Pruitt broke from the hearing at 11 a.m. to attend a meeting at the White House with President Trump on the EPA’s Renewable Fuel Standard, but was expected to return to the committee by 2 p.m.

Pruitt used the start of the hearing to defend his record at the EPA, which has included an extensive rollback of rules and regulations related to climate change and an emphasis on working closer with states and industry.

“As an agency, we must ensure that we are acting within the parameters which Congress has laid out for us,” Pruitt said, using familiar phrases such as “rule of law,” “back to the basics” and “cooperative federalism.”

Democrats attacked Pruitt for his approach.

"EPA has all the signs of an agency captured by industry," said Rep. Paul Tonko, D-N.Y., who later criticized Pruitt for installing a policy that bars scientists who receive EPA grants from serving on agency review boards. Ruiz also said Pruitt did not properly consider science in moving to repeal the Clean Power Plan.

But Pruitt sought to assure lawmakers he values science.

"Science is essential and will remain central and core to what we do,” he said.

The Clean Power Plan, intended to reduce power plant emissions, was the main U.S. pledge as part of the international Paris climate change agreement, which the Trump administration intends to leave.

The plan would have required requires states to reduce carbon dioxide emissions by 32 percent below 2005 levels by 2030. The plan never went into effect because the Supreme Court stayed the rule as it made its way through the courts.

But even the fiercest critics of the plan say Pruitt may not be able to repeal the rule without replacing it because of the endangerment finding, and the EPA administrator seems to recognize that.

Pruitt is expected to soon issue a notice seeking comment on how to proceed. EPA will accept comments on its proposed repeal through Jan. 16.

Congressional Democrats have long asked for Pruitt to appear before them, and were upset the EPA administrator had to break early from his testimony before coming back later.

“This is not the way any agency is supposed to interact with its authorizing committee,” said Rep. Frank Pallone of New Jersey, the top Democrat of the Energy and Commerce Committee. “The lack of transparency and cooperation from this administration is completely unprecedented.”

Pruitt replied that he intends to cooperate with the committee moving forward, even with Democrats who disagree with his approach.

“This dialogue that begins today is important to me," Pruitt said. "I seek to engage in a civil discourse with you.”