Mary Nichols no longer appears to be running to help E.P.A.

“If I were Joe Biden and I was looking for someone to implement the green agenda, I would pick Mary Nichols,” said Steven J. Milloy, who led Mr. Trump’s transition team and now runs a website that has the wrong information about the climate advertised are change. “She’s dedicated, she’s experienced, she knows the job back and forth. I don’t approve of a single thing she does. She’s an environmentalist who’s fucking ahead of the torpedoes at full speed.”

Ms. Nichols, 75, was first named director of California’s Clean Air Program by Governor Jerry Brown in 1979. In the decades since then, she has been at the forefront of this program as California led the way in environmental policy, adopting ambitious statewide pollution control and conservation measures that often served as models for national and national action, including international environmental law.

During the Clinton administration she joined the E.P.A. She then returned to California as chief cleaner for clean air, where she led the state’s pioneering program on climate change under Governor Arnold Schwarzenegger. During the Obama administration, it was Ms. Nichols who helped broker an agreement with the federal government and the country’s largest automakers who adopted California’s stringent global warming regulations for auto emissions and applied them nationwide. Just as Mr Obama borrowed clean air and climate change strategies from California, Mr Biden is widely expected to do so.

In an interview last week, when she was still a top contender for the E.P.A. Ms. Nichols strongly pushed back on claiming she was insensitive to environmental justice issues.

“California is a world leader in efforts to draw attention and funding to underfunded communities,” she said.

Ms. Nichols noted that the primary objection from environmental groups was that they were in favor of California’s cap-and-trade policy, a system whereby the state exacerbates greenhouse gas emissions from stationary sources but allows businesses to buy and sell permits .

She noted that the program had been introduced because it was preferred by Mr. Schwarzenegger, the Republican governor, who passed the state’s Climate Change Act in 2006 and recruited them to implement it in 2007.