Conservationists are challenging U.S. Sen. Craig Thomas' proposed revisions to the Endangered Species Act.

Thomas, R-Wyo., wants to make it more difficult to petition for a species to be protected under the federal law. He introduced his "Endangered Species Listing and Delisting Process Reform Act of 2003" last week.

Thomas' proposal would establish minimum requirements for a listing petition, including an analysis of the status of the species, its range, population trends and threats. It requires that each listing be supported by sound science and seeks to make it easier to delist a listed species.

Jeff Kessler, conservation director of the Biodiversity Conservation Alliance in Laramie, said Thomas is trying to weaken the Endangered Species Act. He challenged whether Thomas could find any examples of species being easily listed.

"Take this out of the rhetorical realm and show some real examples," he said.

Thomas' implication that scientific data is not used in listing endangered species is "just flat wrong," Kessler said.

The best way to improve the Endangered Species Act is to increase funding for helping endangered species recover and get federal agencies, particularly land agencies, to follow environmental protection laws, he said.

In addition, Kessler said, leaders in Washington need to make a serious commitment to save endangered species.

Under Thomas' proposal, the secretary of Interior also would determine if sufficient biological information exists to support a recovery program. Thomas' proposal would give a more substantial role to the states and general public in determining which species are endangered.