Two years ago, Nevada Attorney General Adam Laxalt quietly enlisted the Silver State in a ferocious fight to keep fraud investigators from scrutinizing groups connected to some of his largest future campaign backers.

Laxalt, the Republican nominee for Nevada governor, entered the fray after a 2015 investigative series by InsideClimate News prompted a multi-state investigation into ExxonMobil’s alleged role in downplaying climate change.

A subpoena issued to the Irving, Tex.-based oil company also named several organizations funded by oil industry billionaires Charles and David Koch — the GOP megadonors behind groups that have since spent $2.5 million to support Laxalt’s governor campaign.

Letters and legal briefs signed by Laxalt in 2016 condemned the inquiry as a political probe meant to stifle an “ongoing public policy debate” over human-caused global warming.

The push to prevent an Exxon inquiry is far from Laxalt’s only foray into legal battles beyond Nevada's borders. Political opponents have slammed the GOP governor hopeful for signing the state on to a half-dozen friend-of-the-court briefs on topics ranging from abortion to clean air regulations.

MORE:Why Adam Laxalt is toxic for Nevada: Macquarie

For them, Laxalt’s objections to the Exxon inquiries count as yet more evidence of his willingness to use his office to push a political agenda.

Laxalt's office said in a statement that he objected to the Exxon probe on free speech grounds. The statement did not directly address questions about whether Laxalt's opposition to the investigation played any role in the campaign backing he has since received from Koch-funded organizations.

"Attorney General Laxalt has a strong record of protecting Nevada’s natural resources and zealously protecting the integrity and public perception of the Office of the Attorney General," wrote office spokeswoman Monica Moazez. "The brief and the letter that Attorney General Laxalt joined expressly disavowed taking any position on global warming; they took a strong position against chilling speech."

Laxalt said through a campaign spokesman that he believed humans play a role in climate change. It's important, he added, for policymakers to take a "reasonable approach to these things while protecting our jobs and the economy.”

Anne Macquarie, chair of the Sierra Club's Toiyabe chapter, urged him to take a different tack.

"Nevada already is suffering the effects of climate disruption in increased wildfires, droughts, and extreme heat events. It will get worse," she said. "We need public officials who watch out for the interests of all Nevadans and work for a healthy state for all, rather than using their office to pursue an extreme ideological agenda.

"We are concerned that if elected governor, Laxalt will continue to do the same."

'A public policy debate'

Wrangling over Exxon’s alleged climate change-confusion campaign dates back to 2015, when an award-winning investigation from InsideClimate News suggested the company ignored in-house scientists' warnings about the dangers of burning fossil fuels.

Rather than reveal what researchers had learned, reporters found, the company quickly pivoted to “manufacturing doubt about the scientific consensus that its own scientists had confirmed.”

The news coverage caught the attention of attorneys general in New York and Massachusetts, who launched ongoing probes into what the company knew and whether it had misled investors about the globe-warming perils of its products.

Exxon sued to block the investigations. One day later, Laxalt and a dozen GOP colleagues weighed in with a scathing missive supporting Exxon’s position.

“We think this effort by our colleagues to police the global warming debate through the power of the subpoena is a grave mistake,” they wrote in a letter addressed to their fellow attorneys general. “Using law enforcement authority to resolve a public policy debate undermines the trust invested in our offices and threatens free speech.”

Laxalt followed that up with a September 2016 amicus brief that dismissed the Exxon probe as the product of a “cultural movement” that sought to promote a clean energy-focused “social ideology” at the expense of a “vigorous debate” about global warming.

Exxon allies, including several well-known Koch brothers affiliates named in a subpoena, took out a full-page ad in the New York Times denouncing the investigation and warning that law enforcement officials “should never use their powers to silence participants in political debates.”

Then, as now, human-caused climate change is not subject to much debate in the scientific community. It is the prevailing view endorsed by national science academies in every major industrialized country. Studies show it also remains a long-settled point of consensus among the vast majority of published climate researchers.

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Nevada environmental advocates said Laxalt's efforts to halt the Exxon investigation amounted to an attempt to erode that consensus.

"This was a very concerning action," said Andy Maggi, executive director of the Nevada Conservation League. "The letter he signed onto undermines the established science of climate change and attempts to draw a parallel between those that deny the facts of climate change and those advocating for action to reduce carbon pollution.

"But Adam Laxalt has a history of putting polluters ahead of the Nevadans. Especially when it comes to clean air, climate, and energy."

The political arm of Maggi's organization has pledged to spend more than $1 million to defeat Laxalt's campaign. The Sierra Club, too, explicitly opposes his bid for the governor's office.

Judge tosses out Laxalt letter

Despite Laxalt's intervention, efforts to derail the Exxon probes haven’t gained much traction in court.

A federal judge in March dismissed the company’s case against attorneys general in Massachusetts and New York, who initiated the investigation under state anti-fraud statutes.

Judge Valerie E. Caproni, of U.S. District Court for the Southern District of New York, likened the pro-Exxon letter penned by Laxalt and other Republicans to a “heckler’s veto” unworthy of consideration as evidence.

The Massachusetts Supreme Court also upheld state Attorney General Maura Healey’s right to continue pursuing the investigation.

Last year, a lower court judge ruled that ExxonMobil must turn over 40 years of documents on climate change sought by Healey and ex-New York Attorney General Eric Schneiderman.

New York’s attorney general’s office last month told a judge that they were nearing the end of their two-year investigation. The Trump administration has dropped a similar inquiry into Exxon. That probe was first opened by the Securities and Exchange Commission under President Barack Obama.

Laxalt, who has embraced Trump on the campaign trail, in February endorsed a multi-state legal fight against Obama's plan to curtail greenhouse gas emissions with an opinion that says states have a right to decide pollution emission standards for themselves.

In June, the Las Vegas Review-Journal reported he had aided legal efforts to prevent California from revealing donors to the Americans for Prosperity Foundation, a prominent Koch-backed political nonprofit.

Within a year, Freedom Partners Action Fund, another Koch-linked advocacy group, announced the first stage of a multimillion-dollar television and digital advertisement blitz to boost Laxalt's gubernatorial bid.

Democrats have blasted Laxalt for signing on to four other known amicus briefs backing abortion restrictions or pro-life organizations outside of Nevada.