WASHINGTON, DC - MARCH 04: MIT professor Ernest Moniz (L) , nominated as Energy Secretary, and Sylvia Mathews Burwell (R), the President of the Walmart Foundation nominated as budget director, applaud as U.S. President Barack Obama announces Gina McCarthy (C), as his nominee to head the Environmental Protection Agency during a ceremony in the East Room of the White House March 4, 2013 in Washington, DC. The nominations will be key appointments for Obama's second term while focusing on the issues of the national budget as well as energy and climate issues. (Photo by Win McNamee/Getty Images) Energy Secretary Ernest Moniz (left) and Sylvia Mathews Burwell (right), applaud as Gina McCarthy (center) is nominated to become head of the Environmental Protection Agency. (Win McNamee/Getty Images)

After fielding an unprecedented number of questions and coming under sharp attack from several Republicans, Environmental Protection Agency official Gina McCarthy won Senate confirmation to head the agency in a 59 to 40 vote.

McCarthy, who headed the EPA's air and radiation office during Obama's first term, has played a key role in the administration's efforts to address global warming as well as curb traditional pollutants such as soot and mercury. Environmentalists see her as a key ally in efforts to limit greenhouse gas emissions from power plants over the next few years, but she has also won praise from business officials who view her as open to compromise.

On Wednesday, for example, the American Gas Association president Dave McCurdy issued a statement saying, "Gina McCarthy and I have a constructive working relationship based on an open and honest dialogue that will continue as we work towards the shared goal of improving the data available on the environmental impact of natural gas."

President Obama welcomed McCarthy's confirmation in a statement, calling her, "a proven leader who knows how to build bipartisan support for commonsense environmental solutions that protect the health and safety of our kids while promoting economic growth," adding he looks "forward to having her in my Cabinet as we work to slow the effects of climate change and leave a cleaner environment for future generations."

Environmentalists and their congressional allies celebrated the news as soon as the vote was final. In an interview Margie Alt, executive director of Environment America, called McCarthy's confirmation "the best thing that can happen for our air and our water and our land," while League of Conservation Voters president Gene Karpinski said, "It's about time. Now it's time for her to roll up her sleeves and get to work, and get the job done."

A veteran of Republican administrations in Massachusetts and Connecticut, McCarthy has devoted much of the past four years to shepherding through air regulations that have protected public health — but that also have helped shutter power plants emitting greenhouse gases linked to climate change. While Obama picked her more than four months ago to succeed former EPA administrator Lisa P. Jackson, McCarthy -- who met personally with at least 60 senators -- came under intense scrutiny as several senators used her nomination as a way to highlight their problems with the president's environmental agenda.

McCarthy received more than 1,100 questions from the Environment and Public Works Committee, all but 25 of which came from Republicans. The panel's top Republican senator David Vitter (La.) posed 600 of them, according to the panel’s majority office; during the debate Thursday on McCarthy's nomination, he declared, "This agency overreach has been historic."

Some members of the coal industry quietly opposed McCarthy's confirmation and one of the lawmakers most closely aligned with coal producers, West Virginia Sen. Joe Manchin, was the lone Democrat voting against her. In a statement, Manchin said that "my fight is not with her," though he does "not believe she is the leader who we are looking for" given the fact that "she has been responsible for overseeing some of EPA’s most unreasonable and restrictive proposals" in her current role at EPA.

"My fight is with President Obama and the EPA, the regulatory agency that has consistently placed unreasonable regulations and unobtainable standards on energy production, rather than focus on efforts to develop a domestic all-of-the-above energy strategy for the future," Manchin added.

But shortly after McCarthy was confirmed the CEO of the  National Mining Association, Hal Quinn, released a statement saying his group "stands ready to work with Gina McCarthy, the newly-confirmed EPA administrator, and her staff toward thoughtful, constructive policies that assure America’s mining industry continues to provide the energy, metals and minerals all Americans depend on for economic security and quality of life.”

Six Republicans voted in favor of McCarthy's appointment, several of whom are more moderate: Lamar Alexander (Tenn.), Kelly Ayotte (N.H.), Susan Collins (Maine), Bob Corker (Tenn.), Jeff Flake (Ariz.) and John McCain (Ariz.). Sen. Roger Wicker (R-Miss.) did not vote.

Since Jackson's departure, EPA deputy administrator Bob Perciasepe has been serving as the agency’s acting administrator.