Environmental Protection Agency Administrator Lisa Jackson is calling it quits after nearly four years at the EPA.
Jackson announced her resignation in a statement Thursday. She gave no reason for leaving, but she said she is ready for new challenges, time with her family and new opportunities.
Jackson is known for her bouts with industry and congressional Republicans over global warming, pollution, the Keystone XL oil pipeline and new controls on coal-fired plants.
Jackson is expected to leave after the State of the Union in late January.