The Senate on Thursday morning approved the nomination of Bill Wehrum to lead the Environmental Protection Agency’s Office of Air and Radiation.

The party-line vote was 49-47, with only Republican Sen. Susan Collins of Maine switching over with Democrats to reject Wehrum. Four senators did not vote.

Democrats uniformly opposed his nomination, saying his ties to business prevent him from being an effective and faithful environmental enforcer.

"Wehrum has spent much of his career fighting to dismantle federal environmental protections upon which states depend to clean toxic air pollution," said Sen. Tom Carper of Delaware, the top Democrat of the Senate Environment and Public Works Committee, in a lengthy floor speech Thursday before the vote. "He continues to believe the EPA never intended to address climate change under the Clean Air Act. Suffice to say, his views are not just curious, they are dangerous."

One Democrat, Sen. Tammy Duckworth of Illinois, had placed a hold on Wehrum’s confirmation last month to block him from being considered on the floor.

Wehrum, an energy industry lawyer and former acting administrator of the EPA's air office, will oversee a portfolio dealing with climate change regulations.

The post is widely considered the EPA's second most important job, and Democrats say Wehrum's industry ties would complicate his ability to re-evaluate carbon emissions regulations that EPA Administrator Scott Pruitt has tapped for review, such as the Clean Power Plan.

Republicans, meanwhile, say Wehrum's credentials make him well suited to undo Obama administration regulations they view as overly burdensome and costly.

“Under the Obama administration, the air office was one of the biggest regulatory abusers,” said Sen. John Barrasso, R-Wyo., chairman of the Environment and Public Works Committee. “Mr. Wehrum is going to play a key role in undoing this red tape. [His] expertise and experience will be tremendously helpful as he pursues policies that will protect America’s air, undo regulatory overreach, and allow our economy to grow.”

Concerns over his industry connections led to Wehrum being rejected by Congress to serve in the same position in the George W. Bush administration.

In his private law practice, Wehrum's clients have included the American Petroleum Institute, American Fuel and Petrochemical Manufacturers, the American Chemistry Council, and the National Association of Manufacturers.

Wehrum during his confirmation hearing in October suggested he would be faithful to Trump's deregulatory agenda, which at the EPA is being carried out by Pruitt, who had close ties to the energy industry in his previous job as Oklahoma's attorney general.

"President Trump and Administrator Pruitt have set a clear agenda that I intend to implement if confirmed to this position," Wehrum said. "The president has issued executive orders that will eliminate needless and burdensome regulations, simplify and streamline compliance obligations, and strike a better balance between the twin goals of protecting human health and the environment and promoting the economic vitality of the nation."

That perspective mirrors how Pruitt talks about his job, Democrats noted, complaining that phrases such as "balance" downplay many scientists' belief that humans are a major contributor to climate change by burning fossil fuels that emit greenhouse gases.

Wehrum acknowledged in his confirmation hearing that humans are contributing to climate change. But he said "it's an open question" if humans are the predominant cause of global warming, a position held by other Trump administration officials.

The Environment and Public Works Committee advanced Wehrum’s nomination last month, but only after delaying a vote after Republicans threatened to oppose him because of the Trump administration's proposal to weaken the Renewable Fuel Standard, which requires a certain amount of biofuels to be blended into the nation's fuel supply.

Sen. Joni Ernst, from the corn-producing state of Iowa and a major supporter of the Renewable Fuel Standard, had criticized Wehrum for being insufficiently supportive of the biofuel industry.

Ernst and other Midwestern senators changed course after Pruitt backtracked and assured he would maintain the Renewable Fuel Standard.

The EPA is awaiting a full Senate confirmation vote for Michael Dourson to run the Office of Chemical Safety and Pollution Prevention.

Dourson advanced out of committee with Wehrum, but the former is particularly contentious and his confirmation by the Senate is not promised.

Dourson, a toxicologist and University of Cincinnati professor, has been criticized for his ties to the chemical industry, which he would be expected to regulate. He founded a consulting group that represented companies that produced chemicals now under EPA review for their public health risks.

Democrats have expressed concern that Dourson is already working at the EPA as a top adviser to Pruitt despite being unconfirmed.

A coalition of 10 senators wrote in an Oct. 24 letter to the EPA that Dourson's advisory role at the agency may violate the Federal Vacancies Reform Act.

The federal law prohibits most people who have been nominated to fill a vacant government position from doing that office's duties in an acting capacity.