The US Senate has confirmed a former oil and gas lobbyist as secretary of the Interior Department, an appointment that critics say elevates a "dangerous, unqualified, and conflicted" individual to a post overseeing the permitting process for a fossil fuel drilling in a large swath of the United States.

David Bernhardt was confirmed 56-41, with senators largely voting along party lines for Donald Trump's nominee.

Mr Bernhardt's confirmation comes in spite of persistent ethical concerns, and doubts that he could conduct oversight of the Interior Department independently, given his previous employment as a lobbyist advocating on behalf of oil and gas interests during the Obama administration.

In the days leading to the vote, Mr Bernhardt's nomination had attracted plenty of protests in Washington, including those who showed a penchant for theatrics by marching on Senate majority leader Mitch McConnell's office wearing swamp creature costumes. Democrats, meanwhile, warned that the confirmation was being rushed and constituted a danger to American resources — and at least eight senators alongside four government watchdog groups urged the Interior's inspector general to open an investigation into Mr Bernhardt.

"McConnell just rushed David Bernhardt's nomination through the Senate. Bernhardt sets a new standard for dangerous, unqualified, and conflicted cabinet members in the Trump administration," tweeted senator Ron Wyden.

Inside Mar-a-Lago - Trump's holiday home Show all 20 1 /20 Inside Mar-a-Lago - Trump's holiday home Inside Mar-a-Lago - Trump's holiday home Donald Trump sits in the living room at Mar-a-Lago in 1993. The following pictures show the interior of the Mar-a-Lago estate. Many of them are from before Trump bought the property in 1985 but, as the newer pictures show, he hasn't done much with the place Rex Inside Mar-a-Lago - Trump's holiday home The dining room at Mar-a-Lago under Trump. The following pictures show the interior of the Mar-a-Lago estate. Many of them are from before Trump bought the property in 1985 but, as the newer pictures show, he hasn't done much with the place Rex Inside Mar-a-Lago - Trump's holiday home The dining room at Mar-a-Lago in 1967. The following pictures show the interior of the Mar-a-Lago estate. Many of them are from before Trump bought the property in 1985 but, as the newer pictures show, he hasn't done much with the place US National Park Service Inside Mar-a-Lago - Trump's holiday home The dining room at Mar-a-Lago under Trump in 2015 The Washington Post/Getty Inside Mar-a-Lago - Trump's holiday home Function room at Mar-a-Lago in 1967 US National Park Service Inside Mar-a-Lago - Trump's holiday home Donald Trump sits in the living room at Mar-a-Lago in 1993. Rex Inside Mar-a-Lago - Trump's holiday home The living room in Mar-a-Lago in 1967 US National Park Service Inside Mar-a-Lago - Trump's holiday home Master bedroom at Mar-a-Lago in 1967 US National Park Service Inside Mar-a-Lago - Trump's holiday home Library at Mar-a-Lago in 1967 US National Park Service Inside Mar-a-Lago - Trump's holiday home Cloister at Mar-a-Lago in 1967 US National Park Service Inside Mar-a-Lago - Trump's holiday home Entrance hall at Mar-a-Lago in 1967 US National Park Service Inside Mar-a-Lago - Trump's holiday home Spiral staircase at Mar-a-Lago in 1967 US National Park Service Inside Mar-a-Lago - Trump's holiday home The dining room at Mar-a-Lago in 1967 US National Park Service Inside Mar-a-Lago - Trump's holiday home Patio at Mar-a-Lago in 1928 US National Park Service Inside Mar-a-Lago - Trump's holiday home Cloister at Mar-a-Lago in 1967 US National Park Service Inside Mar-a-Lago - Trump's holiday home Mar-a-Lago in 2018 Getty Inside Mar-a-Lago - Trump's holiday home Mar-a-Lago in 2018 Getty Inside Mar-a-Lago - Trump's holiday home Mar-a-Lago in 2018 Getty Inside Mar-a-Lago - Trump's holiday home Mar-a-Lago in 2018 Getty Inside Mar-a-Lago - Trump's holiday home Mar-a-Lago in 2018 AFP/Getty

Despite those concerns, Mr Bernhardt has effectively been leading the department for months, ever since former secretary Ryan Zinke resigned in December amid multiple investigations including one that was referred to the Department of Justice to determine if a deal with the oil and gas company Halliburton in his home state Montana constituted a conflict of interest.

Before Mr Zinke's departure, Mr Bernhardt had helped in the effort to expand oil and gas drilling on roughly 500 miles worth of land that the Interior Department controls, and had previously been off-limits for drilling operations.

During Mr Zinke's tenure, the Trump administration's approach to stewardship of the nation's interior had become well known for its efforts to open up drilling in the Arctic National Wildlife Refugee, to expand offshore oil and gas drilling, and to limit the cut the number of animals protected by the endangered species act.

Support free-thinking journalism and attend Independent events

"David Bernhardt spent much of his career lobbing for fossil fuel and agricultural interests, and the president putting him in charge of regulating his former clients is a perfect example of everything wrong with this administration," said House Natural Resources Committee chairman Raul Grijalva following the nomination announcement in February.

"We intend to conduct vigorous oversight of Mr. Bernhardt’s industry ties and how they may influence his policy decisions," Mr Grijalva continued in a statement following the nomination. "This administration has lost the benefit of the doubt, thanks in no small part to Ryan Zinke’s failed tenure at the Interior Department. We expect Mr. Bernhardt to right the ship and will act in his absence if he doesn’t".

Mr Bernhardt is known as a Washington insider, who spent eight years during the Obama administration lobbying on behalf of clients like Samson Resources — the largest privately held crude oil and natural gas company in the US — as well as other heavyweights in the oil industry like Halliburton and the Independent Patroleum Association of America, which is a consortium of thousands of oil and gas companies across the US.

His confirmation was decried by environmental groups.