Robin Nazzaro, a top investigator for the GAO, made the allegation at a House hearing on purported interference by Julie MacDonald, a high-ranking Interior official who resigned last year.
The officials named by Nazzaro are Craig Manson, a former assistant Interior secretary; Brian Waidmann, chief of staff to Interior Secretary Dirk Kempthorne; Todd Willens, a former deputy assistant Interior secretary: and Randal Bowman, a special assistant in the Interior secretary's office.
All four acted in ways that could be seen as interfering in decisions on treatment of endangered species, Nazzaro said. Willens and Manson have left the Interior Department, while Waidmann and Bowman continue to work there.
Manson, Willens and Waidmann were Bush administration appointees, while Bowman is a career Interior official who now works under Lyle Laverty, the current assistant Interior secretary for fish, wildlife and parks.
Nazzaro said she was not accusing the four of wrongdoing, per se, but said memos, e-mails and other documents studied by the GAO show they were involved in decisions later found tainted by political pressure from MacDonald.
A spokeswoman for the Interior Department declined immediate comment. A message was left for Waidmann, and the other three could not immediately be reached.
Last fall, the Fish and Wildlife Service, an arm of the Interior Department, reversed seven rulings that denied endangered species increased protection, after an investigation found the actions were tainted by MacDonald.
But Nazzaro criticized the Fish and Wildlife Service for conducting what she called a too-narrow review. Instead of focusing only on MacDonald, the agency should have broadened its review to include decisions potentially influenced by Manson, Waidmann, Willens, Bowman and other high-ranking Interior officials, she said.
"Questions remain about the extent to which Interior officials other than Ms. MacDonald may have inappropriately influenced (Endangered Species Act) decisions and whether broader ESA policies should be revisited," she said.
Rep. Nick Rahall, D-W.Va., chairman of the House Natural Resources Committee, called Nazzaro's testimony and a 66-page report submitted by GAO troubling.
"A disconcerting picture has emerged of officials working at the highest levels of the Interior Department continuing to tamper with the endangered species program, trumping science with politics," Rahall said. "The practice is pervasive and I am convinced that the only remedy is a house-cleaning, post-November."
Rahall and other Democrats requested the GAO investigation after MacDonald resigned last spring, saying they wanted to uncover whether and how much partisan considerations tainted decisions on whether to list species as endangered.
The report released Wednesday shows "we can have no confidence that political tinkering with the ESA program is being addressed any better now than it was under MacDonald's reign," Rahall said.
