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.