Energy Secretary Steven Chu Resign After 4 Years in Office

Energy Secretary Steven Chu is resigning after serving four years under the Obama administration, he said in a statement released Friday.

"Serving as Secretary of Energy during such a momentous and important time has been incredibly demanding but enormously rewarding. I've been continually impressed by the talent and commitment of the men and women of this Department," Chu wrote in his resignation letter.

"While I will always remain dedicated to the missions of the Department, I informed the President of my decision a few days after the election that Jean and I were eager to return to California. I would like to return to an academic life of teaching and research, but will still work to advance the missions that we have been working on together for the last four years."

Chu won a Nobel Prize in physics but came under questioning for his handling of a solar energy loan. Republicans criticized his handling of a $528 million federal loan to solar panel maker Solyndra, which later went bankrupt, laying off its 1,100 workers.

A number of possible successors had been alluded to in recent months, including former North Dakota senator Byron Dorgan, former Colorado governor Bill Ritter and two major Obama contributors: Tom Steyer, head of one of the world's biggest hedge funds; and Steve Westly, a venture capitalist focusing on renewable energy technology firms.