WASHINGTON (AP) — The ex-oil and gas lobbyist nominated to head the Interior Department faced tough questioning Thursday from Senate Democrats about whether he suppressed staff warnings about the impact of agency decision-making on endangered species.

David Bernhardt appeared Thursday before the Senate Energy and Natural Resources Committee, which is considering his nomination. Bernhardt has been serving as Interior's acting secretary since Ryan Zinke's resignation in December amid ethics allegations.

Bernhardt told senators he aimed to keep "working to reduce regulatory burdens without sacrificing environmental outcomes."

Sen. Ron Wyden, an Oregon Democrat, cited Interior documents recently made public under the federal Freedom of Information Act that he said showed Bernhardt's agency suppressed internal findings about the impact that recent Interior decisions on pesticides would have on wildlife.

"You've meddled with the science, you've inserted yourself in the scientific process," Wyden said.

Bernhardt responded that he made those decisions in accordance with advice from the department's lawyers.

Wyden also spoke critically of Bernhardt's past lobbying work for clients with business before Interior, saying they made it impossible for Bernhardt to impartially decide a host of regulatory matters dealing with the public resources under Interior's control.

"I think you are so conflicted," Wyden said. "You're either going to have to disqualify yourself from so many matters I don't know how you're going to spend your day" or violate ethical standards by not recusing himself from decisions on clients.

Sen. Cory Gardner, a Colorado Republican, defended Bernhardt, saying his past work for industries and previous stints as a senior staffer at Interior gave him valuable experience.