WASHINGTON (AP) -- Former Colorado Senator Ken Salazar plans to step down as U.S. Interior Secretary in March.

Salazar oversaw a moratorium on offshore drilling after the BP oil spill and promoted alternative energy sources throughout the nation.

He also pushed renewable power such as solar and wind and the settlement of a longstanding dispute with American Indians.

In a statement, President Barack Obama said Salazar had helped "usher in a new era of conservation for our nation's land, water and wildlife."

Salazar said the Interior Department was helping secure "a new energy frontier, ushering in a conservation agenda for the 21st century, and honoring our word to the nation's first Americans."

The 57-year-old Salazar is the latest Cabinet secretary to leave the administration as Obama heads into his second term.