(Reuters) - President Donald Trump’s pick to run the U.S. Department of Interior, a former energy lobbyist, faced tough questions during his Senate confirmation hearing on Thursday about potential conflicts of interest and the administration’s unpopular plan to expand offshore oil drilling.

Former energy lobbyist David Bernhardt is sworn in before a Senate Energy and Natural Resources Committee hearing on his nomination of to be Interior secretary, on Capitol Hill in Washington, U.S., March 28, 2019. REUTERS/Yuri Gripas

On the drilling plan, David Bernhardt said it was still in its early stages and would be “winnowed down” to address the concerns of coastal states. That was the clearest sign yet that the Trump administration will need to scale back its initial proposal made more than a year ago to open up nearly all of America’s coastal waters to drilling.

“We’re at step one, not step seven,” Bernhardt told the Senate Energy and Natural Resources Committee, adding the plan had yet to be fully drafted.

“The entire planning process is supposed to do this: start out big and winnow down,” he said.

The initial proposal to open up the Atlantic, Pacific and new parts of the Arctic oceans to offshore drilling drew vehement opposition from nearly every coastal state, mainly over environmental concerns relating to potential oil spills.

Bernhardt made the comments at the hearing to confirm him as permanent head of the Interior Department, which oversees more than one-fifth of the U.S. land surface from Alaska to the Gulf of Mexico. The department has been central to Trump’s policy of boosting domestic crude oil, natural gas and coal production.

Lawmakers opposed to Bernhardt heading the department say his former work as a lobbyist could present conflicts of interest unless he recuses himself from certain issues because he has represented companies that would benefit from decisions to open more lands to development.

Bernhardt, 49, pressed repeatedly about his past lobbying for oil and mining companies, sought to assure lawmakers he would make efforts to avoid conflicts of interest.

Separately on Thursday, two House Democrats sent a letter to Bernhardt saying their committees - Oversight and Reform and Natural Resources - were investigating whether he and other Interior officials were accurately preserving records of their schedule and daily meetings.

He has been acting secretary at the department since December, when his predecessor, Ryan Zinke, resigned amid ethics investigations. Like Zinke, Bernhardt is widely seen as a proponent of expanding energy and mining leasing on public acreage.

Democratic senators pushed back against his confirmation, citing a New York Times report earlier this month that Bernhardt helped block the release of a U.S. Fish and Wildlife Service report. That document, detailing the risks that pesticides pose to endangered species, was one that companies wanted to suppress, the paper said.

“So you asked to come to my office to tell me your ethics are unimpeachable, but these brand new documents I just saw make you sound like just another corrupt official,” said Senator Ron Wyden of Oregon. “Why would you come to my office to lie to me about your ethics?”

“I make decisions based on exactly the same standards on every single thing that comes to my desk,” Bernhardt responded.

Slideshow ( 7 images )

Asked if he had anything further to say at the end of the hearing, Bernhardt said: “I certainly didn’t lie to the senator.”

Bernhardt said he was “actually pretty good at going up against these guys,” referring to companies.

A Colorado native, Bernhardt held a series of positions at the Interior Department under former Republican President George W. Bush from 2001 to early 2009, including as solicitor.

Bernhardt, a lawyer, worked for Denver firm Brownstein Hyatt Farber Schreck and as a lobbyist representing Noble Energy Inc, Rosemont Copper Co, Sempra Energy, and California’s Westlands Water District, among other clients.

If approved by the panel, Bernhardt’s nomination will advance to the Republican-controlled Senate where he is widely expected to get the nod.