Chairman of the Senate Environment and Public Works Committee John Barrasso (R-Wyo.) on Monday unveiled draft legislation to overhaul the Endangered Species Act (ESA) in a move that conservationists warn could jeopardize the progress that’s been made through the landmark law and limit future initiatives to save various species from extinction.

“It’s a bill which, on a broad basis, rewrites the ESA, with a whole host of consequences—as far as we can tell, almost entirely adverse consequences—for the protection of species,” Bob Dreher, senior vice president for conservation programs at Defenders of Wildlife, told The Hill. “This bill is all about politics. It’s not about science. It’s especially not about better ways to conserve endangered species.”

Barrasso is a longtime critic of the ESA, and advocates for animals have slammed his ongoing “modernization” efforts as “a smokescreen for a vicious attack on this vital conservation law.” This new proposal, Barrasso said, would increase input from state and regional officials, landowners, and “other stakeholders” in listing and conservation decisions, partly by enabling states to establish species’ recovery teams that could “modify a recovery goal, habitat objective, or other established criteria, by unanimous vote with the approval of the secretary of the Interior.”

It would also, the Casper Star-Tribune noted, “prohibit scientific data from being disclosed in a public records request—if it includes a business or private landowner’s proprietary information. Otherwise, the scientific basis of decisions with a species is to be public information.”