And Trump will be able to try for more than that. For what distinguishes Pruitt’s career is not just his opposition to using regulation to tackle climate change, but his opposition to using regulation to tackle any environmental problem at all. Since he was elected Oklahoma’s attorney general, in 2010, Pruitt has racked up a sizable record—impressive in its number of lawsuits if not in its number of victories—of suing the EPA.

Many of these suits did not target climate-related policies. Instead, they singled out anti-pollution measures, initiated under previous presidential administrations, that tend to be popular with the public.

In 2014, for instance, Pruitt sued to block the EPA’s Regional Haze Rule. The rule is built on a 15-year-old program meant to ensure that air around national parks is especially clear. Pruitt lost his case.

Last year, he sued to block a rule restricting how much mercury could be emitted into the air by coal plants. He lost that, too.

And early in his tenure, he sued to keep the EPA from settling lawsuits brought by environmental groups like the Sierra Club. That one was dismissed.

He has brought other suits against EPA anti-pollution programs—like one against new rules meant to reduce the amount of ozone in the air—that haven’t been heard in court yet. While ozone is beneficial to humans high in the atmosphere, it can be intensely damaging when it accumulates at ground level, worsening asthma and inducing premature deaths. The American Lung Association calls it “one of the most dangerous” pollutants in the United States.

All this is not to say that Pruitt has omitted climate regulations from his litigation. His most common target has been the Clean Power Plan, the Obama administration’s set of Clean Air Act rules meant to reduce greenhouse gas emissions from power plants. The Clean Power Plan is Obama’s main mechanism for pushing the United States to meet its pledge under the Paris Agreement.

Pruitt began suing the EPA to block the Clean Power Plan more than two years ago. Now, Oklahoma is one of the 28 states challenging the agency in court, and it helped succeed in getting the Supreme Court to block the rules in February.

As I wrote in September, there are valid legal reasons that lawmakers might oppose aspects of the Clean Power Plan. Lawrence Tribe, President Obama’s old law-school mentor, argued in court that he believes some of its provisions go too far in asserting federal power. A cap-and-trade component is particularly controversial.

But Pruitt’s understanding of the bill seems not entirely legally minded in two significant ways. First, Pruitt’s knowledge of global warming appears lacking, at best. Earlier this year, for instance, he wrote in the National Review that “scientists continue to disagree about the degree and extent of global warming and its connection to the actions of mankind.”