Two Republican attorneys general have come out fighting against a sweeping investigation into whether ExxonMobil misled the public on global warming, asking a judge to block a subpoena that they call an abuse of power -- and a threat to First Amendment rights.

Texas Attorney General Ken Paxton and Alabama Attorney General Luther Strange asked a Texas state judge Monday to put an end to the investigation being pursued by Virgin Islands Attorney General Claude Walker.

Walker, an independent, issued a subpoena in March seeking 40 years' worth of Exxon communications with 90 conservative groups “and any other organizations engaged in research or advocacy concerning Climate Change or policies.” Walker claims the company misled the public on climate change by downplaying the risks.

But Paxton called the subpoena against the Texas-based company “a fishing expedition of the worst kind.”

“This case is about abusing the power of the subpoena to force Exxon to turn over many decades’ worth of records, so an attorney general with an agenda can pore over them in hopes of finding something incriminating,” Paxton said in a statement. “[It] ... represents an effort to punish Exxon for daring to hold an opinion on climate change that differs from that of radical environmentalists.”

Walker’s office did not respond to a request for comment from FoxNews.com.

The subpoena is part of a broader battle against the oil giant by a coalition of 20 attorneys generals, led by New York’s Eric Schneiderman, and environmental groups.

While a number of states -- including Massachusetts, Vermont and California -- have launched different investigations against the company, they generally aim to replicate the success of the federal government’s 1999 case against Big Tobacco, in which the industry was accused of misleading the public about smoking and nicotine risks.

Schneiderman, who himself subpoenaed Exxon’s financial records and emails last November, has indicated ExxonMobil is not the only energy company in his office's crosshairs, vowing to prosecute any that committed fraud to maximize profit at the public's expense “to the fullest extent of the law.”

Exxon challenged the Virgin Islands’ subpoena in March, dismissing it as “politically motivated and based on discredited reporting by activist organizations.” The company also noted that it does not have any operations or staff located in the Virgin Islands.

A spokesman for Exxon told FoxNews.com Tuesday that they welcomed the intervention by the Texas and Alabama attorneys general.

“We appreciate that Texas and Alabama support our position opposing the Virgin Island’s subpoena for lacking jurisdiction, not recognizing First Amendment rights and the obvious conflict of interest in delegating to a contingency-fee law firm the duty to conduct an impartial investigation,” Alan Jeffers, media relations manager for Exxon, told FoxNews.com.

Meanwhile, a prominent libertarian think tank subpoenaed by Walker as part of the same operation is also going to court, seeking to fine Walker for allegedly violating their First Amendment rights.

The Competitive Enterprise Institute says the subpoena, that sought 10 years of communications regarding its work on climate change, should never have been issued and caused constitutional damage for which it is seeking compensation.

“Mr. Walker’s attempt to silence us and others who share our views is an unconstitutional abomination,” CEI President Kent Lassman said in a statement. “CEI will not sit still with this illegal threat hanging over our head, which is why we are asking the court to fine AG Walker and end his abuse of the legal process to intimidate CEI.”

FoxNews.com’s Adam Shaw and Jennifer Hickey contributed to this report.