Democratic Senator Cory Brooker has said "it's actually hard to come up with someone worse" to run the agency
The US Senate has voted in favour of a long-time opponent of the country's Environmental Protection Agency to run the agency.
The nomination of Scott Pruitt, who previously served as the Oklahoma Attorney General, was confirmed by 52 votes to 46.
Two Democrats voted in favour of Mr Pruitt's nomination, while one Republican voted against.
A majority of Democratic senators, however, had vocally protested Mr Pruitt's nomination.
The New York Times reports senators stayed on the Senate floor all night speaking against Mr Pruitt ahead of Friday's vote. They had also called for a delay to the vote to allow for next week's release of emails related to Mr Pruitt's 'communications with the fossil fuel industry'.
On Twitter, Democratic Senator Cory Booker said Mr Pruitt "filed 14 lawsuits against [the] EPA but didn't even file ONE to reduce air pollution for ~111,000 kids suffering from asthma in his state".
"It's actually hard to come up with someone worse than Scott Pruitt to lead [the] EPA on clean water & air," he added.
It's actually hard to come up with someone worse than Scott Pruitt to lead @EPA on clean water & air. Tell your senator to vote NO.— Sen. Cory Booker (@SenBookerOffice) February 17, 2017
Mr Pruitt has been a vocal critic of Barack Obama's policies on climate change. He also questioned the overwhelming scientific consensus on human-influenced climate change.
In an article co-authored with Alabama attorney general Luther Strange for National Review last year, Mr Pruitt wrote: "Backed by green-energy interests and environmentalist lobbying groups, the coalition has promised to use intrusive investigations, costly litigation, and criminal prosecutions to silence critics of its climate-change agenda."
"Scientists continue to disagree about the degree and extent of global warming and its connection to the actions of mankind," the add.
In a newly published biography on the EPA website, the agency says: "As Administrator, Mr Pruitt’s overarching goal is to lead EPA in a way so that our future generations inherit a better and healthier environment, as he works with the thousands of dedicated public servants at EPA who have devoted their careers to helping realise this shared vision, while faithfully administering environmental laws.
It adds that Mr Pruitt "believes that promoting and protecting a strong and healthy environment is among the lifeblood priorities of the government, and that EPA is vital to that mission".
The confirmation will not alleviate the fears of environmental activists concerned about President Trump's climate and energy plans. He has pledged to undo parts of President Obama's environmental legacy and introduce more industry friendly rules.
On the White House website, the Trump administration says: "For too long, we’ve been held back by burdensome regulations on our energy industry. President Trump is committed to eliminating harmful and unnecessary policies such as the Climate Action Plan and the Waters of the US rule".