By John Schwartz, New York Times

In the eight months since the New York attorney general, Eric T. Schneiderman, announced the first investigation of Exxon Mobil over its past research statements about climate change, nearly 20 other state attorneys general have voiced their support.

But Exxon Mobil has increasingly been pushing back, fighting subpoenas in court and winning the support of lawmakers and friendly state attorneys general who have attacked the investigations as flashy political prosecutions dressed up as legal inquiries.

The company, for example, filed a motion on Wednesday in federal court in Texas to block a demand for documents by the Massachusetts attorney general, Maura Healey, calling it a “fishing expedition.”

The filing argued that Ms. Healey was “abusing the power of government” to silence the company, and that she made statements in a March news conference with Mr. Schneiderman and other state law enforcement officials that suggested she had already made up her mind about what her investigation would find.

On Thursday, Exxon Mobil followed up with a petition in state court in Massachusetts asking the court to recuse Ms. Healey’s office from pursuing the investigation because “it is impermissibly biased” against the company.

Exxon Mobil also argued that the state law that Ms. Healey relied in her investigation has only a four-year statute of limitations.

Alan T. Jeffers, a spokesman for the company, said, “The great irony here is that we’ve acknowledged the risks of climate change for more than a decade, have supported a carbon tax as the better policy option and spent more than $7 billion on research and technologies to reduce emissions.”

A spokeswoman for Ms. Healey, Cyndi Roy Gonzalez, said in a statement that Exxon Mobil’s legal efforts are “an unprecedented effort to limit the ability of state attorneys general to investigate fraud and unfair business practices.”

The law enforcement officials’ actions also have been questioned by Lamar S. Smith of Texas, the Republican chairman of the House Science Committee, and more recently by a coalition of state attorneys general who called the investigations “a grave mistake” that “raises substantial First Amendment concerns.”

Mr. Schneiderman has consistently argued that he is trying to determine whether the company committed fraud by telling investors and consumers one thing while its research showed the opposite. “The First Amendment does not give any corporation the right to commit fraud,” said Eric Soufer, a spokesman for the attorney general.

Mr. Soufer added, “Everything we’ve seen this week is ripped straight from the Big Tobacco playbook: delay, deflect, and distract from any serious investigation into potential fraud or corporate malfeasance.”

Mr. Schneiderman has called the pushback from the company and its supporters “First Amendment opportunism.”

State attorneys general have been at odds over many issues, including the Obama administration’s Affordable Care Act and Clean Power Plan. But the sniping among conservative and liberal attorneys general has been especially heated over Exxon Mobil.

The letter this week from the coalition of conservative state attorneys general, led by Luther Strange of Alabama, stated that Mr. Schneiderman and his allies are “using law enforcement authority to resolve a public policy debate” that is not suited to the courts.

Exxon Mobil went to court in April to oppose subpoenas issued by Claude E. Walker, the attorney general of the Virgin Islands. The Competitive Enterprise Institute, a libertarian advocacy group that also received a subpoena from Mr. Walker, filed a motion against him under a law limiting malicious or frivolous lawsuits intended to suppress speech.

Mr. Walker, who had tried to reassure the group it was not a target, withdrew the subpoena. In a news conference on Thursday, Kent Lassman, the institute’s president, said that “Maura Healey is on a witch hunt” and Mr. Schneiderman is involved in “a conspiracy to punish dissent.”

During Exxon Mobil’s years of funding organizations that undercut climate science, the Competitive Enterprise Institute received about $2 million from the company and its affiliated foundations, according to records obtained by the Climate Investigations Center.

“The reason C.E.I. is so up in arms about these subpoenas is their fear of revealing their dirty laundry,” said Kert Davies, the founder of the investigations center, in reference to Competitive Enterprise Institute.

Sam Kazman, the general counsel for the institute, said that the organization does not disclose donor information. He called Mr. Davies’s suggestions about the group’s motives “whistling in the dark.”

While it has fought some investigators fiercely, Exxon Mobil has provided hundreds of thousands of pages of documents in response to Mr. Schneiderman’s office.

And Robert C. Post, the dean of Yale Law School and a constitutional scholar, rejected the notion that Exxon Mobil is being gagged by the state efforts.

“Debate is not being suppressed in any way by this,” he said, adding that citing First Amendment rights has become “a weapon in the arsenal of those who would seek to unravel the regulatory state.”

“They’re bringing it up because it sounds good.”

To Learn More:

Big Oil Shareholders Reveal Support for Environmental Proposals, Even as They Reject Them (by David Koenig, Associated Press)

Investigations Grow into Alleged Exxon Mobil Climate-Change Deception (by Jake Pearson, Associated Press)

ExxonMobil May Only Be First of Oil Giants to Be Investigated for Obscuring Climate Science (by Steve Straehley, AllGov)

Oil Industry “Million-Dollar Smokescreen” Dooms Gasoline Cuts in Climate Bill (by Ken Broder, AllGov California)

Science Museums, Some Backed by Big Oil, Take Evasive Approach to Climate Change (by Noel Brinkerhoff and Steve Straehley, AllGov)