Interior Secretary Ken Salazar plans to leave the agency at the end of March to return to his family in his home state of Colorado, ending just over four years of service.

Salazar's decision, which was first reported by The Denver Post and confirmed this morning by an agency source, is expected to be made official later today.

The departure of Salazar, a former Democratic senator from Colorado, will create another gaping hole in President Obama's second-term Cabinet and could potentially set up a bruising confirmation process.

U.S. EPA Administrator Lisa Jackson has indicated she plans to leave the Cabinet in the next few weeks, and Energy Secretary Steven Chu is widely expected to also leave the administration.

In his four years at Interior, Salazar led a massive overhaul of the scandal-plagued Minerals Management Service in the wake of the Deepwater Horizon spill in the Gulf of Mexico; introduced sweeping plans to expand solar energy in the Southwest and offshore wind in the Atlantic Ocean; and established comprehensive oil and gas leasing reforms on millions of acres of Western public lands.

Salazar is returning to Colorado to be with his wife and his 5-year-old granddaughter, who has autism and is enrolled in a special school, the Post reported.