Some activists who deny established climate-change science, like Myron Ebell at the Competitive Enterprise Institute, a libertarian think tank, support Mr. van der Vaart’s potential nomination, saying he combines more than 25 years of regulatory experience with a unique background as both a lawyer and chemical engineer. In addition, Mr. Ebell said, Mr. van der Vaart’s climate views are closely aligned with those of the previous nominee, Kathleen Hartnett White, who was withdrawn from consideration this month.

Image Donald van der Vaart said he had been in discussions about possibly leading the Council on Environmental Quality. Credit... North Carolina Department of Environmental Quality

“Having lost Kathleen, which saddens me, I think Donald van der Vaart is a good alternative. He brings many of the same strengths,” Mr. Ebell said. And, he noted, “He doesn’t have a long and open trail of speeches and comments,” like Ms. White does, in which opponents can look for ammunition.

Ms. White, a former chairwoman of the Texas Commission on Environmental Quality, came under fire from both parties for her environmental views. Democrats attacked her for suggesting that smog is not harmful and for calling carbon dioxide the “gas of life.” (Carbon dioxide is a major contributor to climate change.) She also said that an E.P.A. standard that requires increasing the amount of ethanol in the nation’s fuel supply should be repealed, angering Midwestern Republicans.

Senator Tom Carper of Delaware, the top Democrat on the Senate Environment and Public Works Committee, said he found Ms. White’s views so unsettling that he mounted a campaign to block her confirmation. Mr. Carper said he visited the offices of 16 Republican senators to voice his concerns, bringing with him an iPad in order to play a three-minute video that his staff had compiled of Ms. White struggling to respond to questions posed by both Republicans and Democrats at her hearing.