Ken Salazar
Interior Secretary Ken Salazar announced today that he will resign by the end of March to return to his home state of Colorado, prompting speculation about a successor.

In a news release, Salazar, 57, said that he fulfilled his promise to President Barack Obama to serve four years as secretary, and that he wanted to return home after eight years in Washington — four as senator and four as an administration official.

The Interior secretary’s job focuses on public lands and energy development, and Salazar is perhaps best known for handling the BP oil spill in the Gulf of Mexico.

But his tenure has included a number of activities affecting the rural economy, including solar, wind and geothermal energy development and “America’s Great Outdoors,” an effort to coordinate with the Agriculture Department to increase rural tourism.

Under Salazar, Interior’s Fish and Wildlife Service and USDA’s Natural Resources Conservation Service have also increased coordination to try to avoid listings on the endangered species list.

While Salazar was secretary, Congress also passed the Cobell settlement to address long-standing injustices regarding the U.S. government’s management of Indian money.

In a statement, Obama said that Salazar “has helped usher in a new era of conservation for our nation’s land, water, and wildlife,” and “played an integral role in my administration’s successful efforts to expand responsible development of our nation’s domestic energy resources.”

“In his work to promote renewable energy projects on our public lands and increase the development of oil and gas production, Ken has ensured that the department’s decisions are driven by the best science and promote the highest safety standards,” Obama said.

“Ken has also made historic strides in strengthening our nation-to-nation relationship with Indian Country, helping to resolve longstanding disputes and make tribal communities safer and stronger. I have valued Ken’s friendship since we both entered the Senate in 2005, and I look forward to receiving his counsel even after he returns to his home state of Colorado.”

Sen. Jon Tester, D-Mont., said that Salazar “did an incredible job bringing a western perspective to this job, honoring American Indians, and managing our natural treasures while responsibly increasing our energy security. “

Tester also said that Salazar led Interior “in establishing science-based conservation strategies while taking steps to increase the nation’s renewable and conventional energy production.”

Potential candidates for Salazar’s job include former Democratic governors Chris Gregoire of Washington and Dave Freudenthal of Wyoming; former Rep. Norm Dicks, D-Wash., former Sen. Byron Dorgan, D-N.D., Deputy Interior Secretary David Hayes, Rep. Raul Grijalva, D-Ariz., and Office of Personnel Management director John Berry, who was a deputy secretary at Interior during the Clinton administration, the Washington Post reported today.