Interior Secretary Ken Salazar is the latest member of the Obama cabinet to depart at the start of the president's second term.
A senior White House official tells ABC News that Salazar has told the president he intends to leave by the end of March. Salazar was a senator representing Colorado from 2005 to 2009 and prior to that the state's attorney general.
One possible replacement is outgoing Washington Gov. Christine Gregoire.
Salazar has run the Interior Department throughout President Barack Obama's first term. Salazar began his tenure with a pledge to help reduce America's dependence on foreign oil. He told his confirmation hearing he would seek to expand renewable energy on public lands and promote the "wise use" of traditional energy sources.
He is the latest Cabinet secretary to leave the administration as Obama heads into his second term. Secretary of State Hillary Rodham Clinton, Pentagon chief Leon Panetta, Treasury Secretary Timothy Geithner and Labor Secretary Hilda Solis are also leaving.
The Associated Press contributed to this report.