(Evan Vucci/AP)

Secretary of Energy Steven Chu announced Friday that he was resigning pending the confirmation of a successor.

The announcement had been anticipated for months. Chu, a Nobel Prize winner in physics and former director of the Lawrence Berkeley National Lab, never seemed comfortable working in the politically charged Washington climate.

In his resignation statement, Chu said he “would like to return to an academic life of teaching and research.” He had come under GOP criticism for a $528 million loan to Solyndra, the now-bankrupt solar panel company.

A number of possible successors had been mentioned 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.