Gavin Newsom, the still boyish but self-assured mayor of San Francisco who traded in a successful career as businessman and restaurateur for the rough and tumble of politics, talked in a wide-ranging interview about why he feels confident as he looks to leave behind a city mired in debt for a much tougher job running California.

Newsom, 41, spent 17 of his formative years in Marin, graduating from Redwood High School, where he attracted notice mainly for his baseball and basketball skills.

His family's move to Marin from San Francisco was prompted by economic necessity - the family could not afford private schools - and cramped space. His parents having divorced, Newsom was raised primarily by his mom who, to make ends meet, rented out their home for a time to a foster family. Newsom was diagnosed in early childhood with dyslexia, a learning disability that afflicts 15 percent of Americans and which he appears to have conquered.

While Newsom claims to have had little interest at first in politics "or even local issues," he remembers with a wry grin that his high school classmates dubbed him "El Presidente."

But when he entered Santa Clara University, political science studies replaced sports and he grew attentive to the burgeoning career of his uncle, former San Francisco Supervisor Ron Pelosi, brother-in-law of the House speaker. "Dinner conversations were about politics," says Newsom.

He attributes his decision to enter the public arena to two people: Willie L. Brown Jr., the wily, indestructible former mayor of San Francisco, and John Burton, the former powerhouse senator and now state Democratic Party chairman. "When Willie first ran for mayor in 1995, I knew the spark had ignited," Newsom said. He campaigned hard for Brown.

Interestingly, the seemingly ageless ex-speaker of the Assembly (Brown celebrated his 75th birthday in March) has aimed some sharp criticisms in recent years at his prot g , whom he plucked out of obscurity to fill a vacancy on the San Francisco Board of Supervisors in 2002.

Since it was Burton who persuaded Brown to appoint Newsom, both could rightly claim to have godfathered the aspiring gubernatorial candidate whose hopes of getting to Sacramento have been realized by only two former San Francisco mayors - "Sunny" Jim Rolph in 1931, and Washington Montgomery Bartlett in 1887.

Is there a geographic bias at work that favors Southern California candidates, where most of the voters reside, and could this make the Hispanic mayor of Los Angeles, Antonio Villaraigosa, a rising star at 56, the one man he must beat?

"No," Newsom said emphatically. "The rules have changed dramatically. We have new demographics in California. Young voters will make the difference." He invokes the words of Robert Kennedy as a mantra: "The answer is to rely upon youth - not a time of life but a state of mind, a temper of will, a quality of imagination, a predominance of courage over timidity."

But what about the emerging Hispanic vote? "I will put my record in that area up against anyone," Newsom said, proudly citing municipal identification legislation he signed that offers protection to illegal immigrants wanting to report crimes and which companies holding public contracts must accept.