A group of state attorneys general announced last year that they were undertaking a probe into whether Exxon Mobil and other corporations misled investors and the public on the risks of climate change. But President-elect Donald Trump’s nominee to lead the Environmental Protection Agency, Scott Pruitt, appears to believe that the probe is stifling “debate” on the issue.

Pruitt, the attorney general of Oklahoma, joined a dozen other Republican attorneys general in signing an open letter on June 15 that argued Exxon’s record on climate change is “not a question for the courts.” The letter, which The Huffington Post reported on earlier this year, was seemingly aimed at the AGs United for Clean Power group, which includes Democratic attorneys general from New York, Massachusetts and California.

Pruitt and the Republican AGs argue that their Democratic counterparts’ probe “targets a particular type of market participant” in focusing only on Exxon Mobil and not similarly targeting clean energy companies or environmental advocacy nonprofits that could be “exaggerating” climate change risks to benefit their bottom line.

The letter goes on to urge the Democratic AGs to “stop policing viewpoints” on climate change, describing the science of climate change as part of a “vigorous debate,” and alleging that the probe “chills” free speech by signaling that “one side of the climate change debate should fear prosecution.”

A lengthy, multi-part investigation by InsideClimate News and The Los Angeles Times previously claimed, based on conversations with former Exxon employees and a review of company documents, that top Exxon executives knew as early as 1977 that fossil fuels contributed to global warming.

Nevertheless, the investigation reports, the company pushed back against initiatives to cut greenhouse gas emissions as part of a campaign that environmentalists have compared to Big Tobacco's previous efforts to downplay the dangers of smoking.

Kathy Mulvey, manager of the climate accountability campaign at the nonprofit Union of Concerned Scientists, described the letter’s assertions as “deeply disturbing” given the volume of evidence that fossil fuel companies like Exxon Mobil may have misled the public on climate change risks.

“I think what we see in this letter and in the efforts by Exxon Mobil and its allies to block these investigations is a twisted interpretation of the first amendment,” Mulvey told The Huffington Post. “Attorneys general have a duty to defend the citizens of their state against fraudulent practices. That there would be an effort by colleagues to prevent even an investigation into these issues is alarming.”

The letter was later a key subject of conversation during a closed-door session on climate change at a Republican Attorneys General Association summit in Colorado in July 2016.

The Center for Media and Democracy confirmed that two signers of the letter, Pruitt and Alabama Attorney General Luther Strange, both planned to participate in a panel titled “Climate Change Debate: How Speech is Being Stifled,” along with Myron Ebell, the climate-denying head of Trump’s EPA transition team and Chet Thompson, president of American Fuel and Petrochemical Manufacturers, a powerful fossil fuel industry group.

Pruitt did not ultimately appear on the panel due to an illness, according to a CMD transcript of the event, but Thompson took the opportunity to thank him and the letter’s other 12 signers for their “instrumental” work “speak[ing] up” for the oil and gas industry.

That collaboration is just one example of a seemingly cozy relationship between Pruitt, other Republican attorneys general and the fossil fuel industry. As a 2014 New York Times investigation revealed, the group of Republican attorneys general appear to be a part of an “unprecedented, secretive alliance” with fossil fuel companies that has worked to fight environmental regulations regulations they reject as federal government overreach.

Industry lobbyists actually drafted the letters Pruitt sent to the EPA and other federal departments objecting to various air pollution and other regulations, according to the Times report. In return, the oil and gas industry contributed more than $215,000 to Pruitt’s two most recent campaigns.

Oil and gas industry groups have also helped fund the work of the Rule of Law Defense Fund, a nonprofit through which Pruitt and other Republican attorneys general coordinated multiple lawsuits targeting the EPA. One of the group’s funders, the Koch-backed Freedom Partners organization, donated at least $175,000 to the organization. Six Democrats on the Senate’s Environmental and Public Works Committee are pressing Pruitt for details on those ties.

With Pruitt now set to lead the EPA ― as long as his confirmation hearing goes well, of course ― environmentalists fear that fossil fuel interests will have unprecedented access to the agency tasked with regulating it. The relationship could severely undermine efforts to reduce climate-changing emissions.

But New York Attorney General Eric Schneiderman and the other Democratic attorneys general leading the Exxon probe do not appear to be backing down.

In a statement provided to HuffPost, Schneiderman said he is “proud to be leading a coalition of states that is already aggressively fighting back against efforts to reverse the progress this country has made in combating climate change over the past eight years.”

Meanwhile, Exxon’s climate change record was back in the spotlight Wednesday morning as the confirmation hearing for Trump secretary of state nominee and former Exxon CEO Rex Tillerson began. Tillerson refused to answer multiple questions on the matter.

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Joseph Erbentraut covers promising innovations and challenges in the areas of food and water. In addition, Erbentraut explores the evolving ways Americans are identifying and defining themselves. Follow Erbentraut on Twitter at @robojojo. Tips? Email joseph.erbentraut@huffingtonpost.com.