After announcing his candidacy this week, Newsom made his pitch to the party faithful by casting himself as the candidate of tomorrow.
"Will we offer Californians a stroll down memory lane?" he said. "Will we embrace the past, or will we embrace the future?"
Newsom, 41, did not mention Brown by name but was clearly drawing a contrast between the party of yesteryear and the ideas he claims to represent. Newsom often has referred to the election of President Barack Obama to say that voters are ready for a fresh start and new ideas.
He played up that theme Saturday, saying his campaign will be about bringing fundamental change to California.
"We're not a state of memories, we're a state of dreams," Newsom said. "We're not intent to keep reliving history; we're going to make it."
Brown, who is three decades older than Newsom, said he is not yet ready to announce whether he intends to run for governor next year. He served two terms as governor in the 1970s and 1980s, and is now the state attorney general.
Newsom also sought to burnish his credentials for the state's top elective office by promoting his record as San Francisco mayor.
He touted the city's universal health care program, solar and clean-energy initiatives, and positive bond rating. Promoting a record of fiscal responsibility will be key for Newsom or whichever Democrat eventually wins next year's nomination.
Never-ending state budget deficits and rising taxes amid the worst state economy in decades have left voters in a sour mood.
"Sound fiscal policy is not a conservative value," Newsom said. "It's just plain common sense."
His address to delegates made only a passing reference to gay marriage, the issue with which he has been most closely associated.