Brown declined to comment.
"Maybe later," the governor said after an event in Oakland, "but nothing today that I can opine on."
Duran later sent out an email confirming his departure, calling it "a true honor" to work for Brown.
His next move? "I am returning to Oakland to continue my public service in the Office of the Attorney General."
Brown has been through numerous press secretaries since he first became governor in 1975. Duran, however, has lasted longer than most. The combative spokesman was an aide and press secretary to Brown when Brown was mayor of Oakland, from 2004 to 2007, and Duran joined the governors' administration in 2011, at the beginning of Brown's third term.
Like many press secretaries, Duran vehemently attacked his boss's critics - from Fox News to legislative Republicans, the latter of which he once called "basically moronic."
Duran could be especially acerbic. He once sent a video of a crying baby to the author of a critical editorial. On Election Night last year, after Lt. Gov. Gavin Newsom had criticized Brown's rhetoric in his campaign to raise taxes, Duran sent Newsom a clip on Twitter of Elvis Presley singing, "Are You Lonesome Tonight?"
Before joining Brown's office, Duran was communications director for U.S. Sen. Dianne Feinstein from 2008 to 2010. He was Los Angeles Mayor Antonio Villaraigosa's press secretary from 2007 to 2008.
Editor's Note: This post was updated to reflect Duran's confirmation of the move. Updated Feb. 12, 2013 at 5:16 p,m.
PHOTO CREDIT: Gil Duran, California Gov. Jerry Brown's press secretary, right, during a news conference in January. The Sacramento Bee/RandallBenton