Lisa Jackson, administrator of the Environmental Protection Agency, announced her resignation.
Jackson, appointed to the cabinet post by President Obama four years ago, said she will leave the position after the president gives his State of the Union address. She said the agency has made historic progress on improving the safety of the nation's air, water and food and moving toward energy independence.
Jackson's tenure was marked by clashes with the meat industry over issues including the Renewable Fuels Standard that mandates ethanol production. The U.S. livestock and poultry industries had called for a waiver during crop shortages.
The Renewable Fuels Association, in a statement, praised Jackson for protecting the progress made on reducing U.S. dependence on foreign oil.