EXCLUSIVE: The Biden administration's recently-announced plan to establish the largest-ever conservation zone was developed in collaboration with left-wing eco groups, according to Montana's attorney general.

In a letter to U.S. Fish and Wildlife Service (FWS) Director Martha Williams, Montana Attorney General Austin Knudsen said he would vehemently oppose her agency's plan to lock up nearly 5.8 million acres in his state and expressed concern that the plan was formulated with left-wing activist groups. The FWS announced the so-called Missouri Headwaters Conservation Area proposal Wednesday.

"Spanning five counties across southwestern Montana, this would be the largest conservation area ever proposed in America," Knudsen wrote to Williams. "The Kafkaesque scheme of environmental laws and regulations in this country already provides a nearly insurmountable obstacle to the energy, mining, and agriculture industries." 

"And this designation would be another tool wielded and abused by well-funded environmental groups to oppose all permits for responsible development on state and private land," he continued. "Most troubling, however, is how this project has come to fruition: behind closed doors and hidden from public scrutiny."

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Knudsen added that his office was shared information that demonstrated the FWS put the proposal to block off land in southwestern Montana together with at least two environmental groups, The Nature Conservancy and Theodore Roosevelt Conservation Partnership. He said leaders from the groups have conducted meetings with local officials to garner support for the proposal.

And, according to Knudsen, FWS failed to consult Montana state officials on the "gargantuan project." The proposed federal wildlife refuge would largely be established with conservation easements on private land, but would also include about 500,000 acres controlled by the State of Montana.

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In its announcement, the FWS said the central purpose of establishing the new conservation zone was "preserving important wildlife habitat and migration corridors and allowing properties to be managed for agricultural use."

"Voluntary private lands conservation has been a success story for wildlife and working lands across Montana for decades," Joel Webster, the vice president of western conservation for the Theodore Roosevelt Conservation Partnership, said in a statement Wednesday. 

"We are excited about this proposal to support Montana farms, ranches, and wildlife habitat, and we encourage the Fish and Wildlife Service to listen to local landowners as they refine the proposal," Webster added.

The Theodore Roosevelt Conservation Partnership said the proposal offers financial options to Montana landowners to maintain their property, protect wildlife and avoid pressure to lease land for resource development like mining or oil drilling.

However, Knudsen said the FWS proposal appears to be a "blatant violation" of the Federal Advisory Committee Act (FACA). That law was passed to "promote transparency, accountability, and open public participation in executive branch decisions and prevent informal advisory committees from exerting improper or one-sided influence."

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"The public deserves — and the law requires — a meaningful opportunity to scrutinize a project of this magnitude, especially one that has been orchestrated surreptitiously with special interests," Knudsen's letter Wednesday continued.

"Montanans deserve better than covert deals between federal bureaucrats and conservation oligarchs," he concluded. "I will vehemently oppose any attempt to ram through this consequential project without full transparency and procedural accountability."

The attorney general further requested all records related to the Missouri Headwaters Conservation Area and for the FWS to postpone any further action until it formally complies with FACA.

The public comment period on the proposal is expected to be open through the end of October.

The FWS, Nature Conservancy and Theodore Roosevelt Conservation Partnership did not respond to requests for comment.