E.P.A. Chief to Step Down

After four frustrating years, Lisa P. Jackson is stepping down from her position as chief as the Environmental Protection Agency. Though she informed staffers in a brief statement Thursday that she was confident “the ship is sailing in the right direction,” her resignation comes as her agency continues to struggle to make climate change a policy priority. Despite the president’s 2008 promise to combat the issue, Jackson’s tenure was instead consume with defending the E.P.A. against challenges from other industries and attacks from the Republican majority over what it called “job-killing regulations.”