In a widely speculated upon move Interior Secretary Salazar is resigning.
Enjoying the strong support of the Obama administration Salazar is said to wish to spend time caring for his autistic granddaughter, as I remember Ken and his wife are the guardians of the child.
At this time it's unknown who the administration is going to nominate in his place. Whomever it is will of necessity be a nominee with appeal to both conservationists and industry. Sec of Int is a big job with many competing interests. The former senator from N Dakota or others have been mentioned but at this point all is speculation.