Citing "a young family and responsibilities at City Hall," Newsom announced Friday that he was quitting the gubernatorial race to spend more time with his wife and newborn daughter.
The telegenic mayor tried to connect with voters at town hall forums across the state, but never finessed his message. He excitedly skipped from topic to topic, promising never to blunt his left-leaning positions on gay marriage, the environment, immigration and universal health care to win votes.
Newsom's campaign hinged on his appeal as a progressive, as he attempted to tap into the currents of change that helped sweep Barack Obama into the White House last year.
But Democrats appeared to prefer the 71-year-old Attorney General Brown, who has formed an exploratory committee but has yet to officially announce he is seeking the nomination.
Brown has maintained a 7-to-1 fundraising edge over Newsom and won heavy financial support from unions, a core Democratic constituency. A Field Poll earlier this month showed Newsom trailing Brown by 20 points among likely Democratic voters.
In a short written statement, Brown wished Newsom and his family well. "Mayor Newsom is a talented public official, and I believe he has a bright future," he said.
Newsom, 42, sought to portray himself as best-suited to usher in a new era for the state, contrasting his vigorous, youthful image with Brown, whom he portrayed as out of touch.
"He looked at the numbers and the numbers weren't good, although he's been on the campaign trail for a while and generated a lot of enthusiasm," said Democratic party chairman John Burton, a longtime family friend of Newsom's.
"He would raise money, but it was going out the door. I just think he looked at it and said it doesn't make sense to do it," Burton said.
Newsom had a team of highly paid political consultants.
Even an early endorsement from former President Bill Clinton was seen as lukewarm and failed to net the anticipated fundraising windfall from Southern California, despite tickets selling at up to $50,000 apiece.
The Democratic nominee is likely to need a large bank account. Two of the three Republicans seeking their party's nomination, Insurance Commissioner Steve Poizner and former eBay chief executive Meg Whitman, are Silicon Valley millionaires. Poizner, Whitman and former congressman Tom Campbell are all social moderates.
Sen. Dianne Feinstein would be the favorite if she chose to enter the Democratic field, a decision she has said she would not make until early next year.
The Field Poll showed neither Brown nor Newsom came close to having Feinstein's appeal. Gil Duran, a spokesman for the senator, said she had "no immediate comment" when asked for her reaction to Newsom's withdrawal from the race.
Burton also dismissed speculation that Feinstein would enter the race, saying the chances were "slim and none and slim left town."
Newsom's successes in San Francisco on such issues as providing universal health care and promoting alternative energy became pillars of his gubernatorial campaign, but also reinforced his image as a liberal who might not be able to capture independents and more conservative Democrats.
