Adithya Sambamurthy/The Bay Citizen

Gavin Newsom fields questions after speaking to supporters on election night

The sun reflecting off his lacquered hair, Mayor Gavin Newsom took the microphone Wednesday afternoon and smiled upon the sea of humanity crammed into the Civic Center to celebrate the Giants’ World Series victory.

“This is why it’s good to be mayor,” Newsom told the crowd at a rally carried live on every major radio and television station in the Bay Area.

Newsom had been elected lieutenant governor the night before. He was ubiquitous during an extraordinary week here, dominating the spotlight to an unusual degree even for a mayor who has occupied the center stage of San Francisco politics for the past seven years.

But change is coming soon for Newsom, 43 , as he prepares to swap San Francisco for Sacramento and take on a low-profile job that he described last year as having “no real authority and no real portfolio.”

How Newsom handles the adjustment and shapes his relationship with Gov.-elect Jerry Brown, 72 , will set the tone of the new administration, political observers and people close to the two men said. It will also determine whether Newsom, who enters as perhaps the highest-profile lieutenant governor in recent memory, will be able to expand the office’s traditionally limited role.

For Newsom, “it’s shifting the gear back a notch,” said John B. Shanley, a former adviser to the mayor. “He’s not going to be the hands-on administrator anymore, getting calls saying, ‘Muni just ran over two people. The police department just had a shooting.’ And that may have been kind of fun for him.”

During his short-lived run for governor last year, Mr. Newsom was critical of Brown, once telling a radio talk show host, “I don’t get the sense there’s fire in his belly.” Newsom will surely try to use his new position to build a résumé for higher office by carving out niche issues like higher education and environmental protection, analysts said — but only if that is what Brown wants.

“The most important thing he can do is establish a good relationship with the governor,” Gray Davis, a former governor and lieutenant governor, said in an interview. “The only way he can expand his portfolio is by winning the trust and confidence of the governor.”

Some state officials are already wondering whether Brown might try to rein in Newsom — some of Newsom’s supporters joke privately that the two men could resemble the sometimes-awkward pairing of President Obama and Hillary Rodham Clinton.

In addition to their generational divide, Brown and Newsom present sharp contrasts in style: Newsom, with his stylish attire and former party-boy image versus the balding Brown, who has positioned himself as the elder statesman of California politics.

“Gavin would be very smart not to appear to be challenging Jerry,” said Darry A. Sragow, a veteran Democratic strategist and occasional adviser to Brown.

Brown is “brilliant and creative and willing to tolerate dissent,” Sragow said. “But if there’s anything that will look like grandstanding, just for the purposes of press or political reasons, he would be stupid not to cut that lieutenant governor off.”

So far, Newsom has treated Brown with deference.

“I look forward to being his lieutenant,” Newsom told reporters last week at a store opening in San Francisco. “We’re going to have the opportunity to have the strongest relationship between lieutenant governor and governor we’ve had in state history, even with Democrats in both offices.”

Political analysts see lessons in the last time two Democrats occupied the state’s highest offices. That ended in disaster.

After Davis was elected governor in 1998, he repeatedly clashed with Lt. Gov. Cruz Bustamante, the first Latino elected to statewide office in 120 years.

At the time, a major issue was whether Mr. Davis should drop the state’s defense of Proposition 187, the 1994 initiative that barred illegal immigrants from receiving health care or education benefits. Bustamante went public to urge Davis to abandon the measure.

“I met with the Gray Davis cabinet for the first few months, but our communication suffered greatly after that,” Bustamante said in an interview. “But I always felt I had to be my own person, not only a loyal No.2.”

The rift widened to the point where Davis took away Bustamante’s parking spaces outside the governor’s office and even tried to squash Bustamante’s bid to spearhead state efforts to maximize the 2000 census count. Bustamante, meanwhile, gave rival speeches after Davis’s State of the State addresses and ultimately competed against him when Davis was recalled in 2003.

Davis said there was a lesson for Newsom. On policy differences, Davis said, “I would recommend that he first bring the matter up privately with the governor, which was not done in our situation.”

Aides for Newsom said that rifts between the two men healed soon after Newsom bowed out of the governor’s race last year. When Newsom took up the race for lieutenant governor, the two camps shared campaign fund-raising information.

In the final month of the campaign, as both Democrats began to pull ahead in the polls and to spend time together on the road, they warmed up to each other, aides said.

In one instance, Brown reacted positively to Newsom’s suggestion that his campaign, and later, their combined administration, could benefit from Newsom’s grasp of social media tools —  Newsom has a large following on Facebook and Twitter. Before a rally headlined by former President Bill Clinton in San Jose last month, Brown and Newsom began to discuss the budget shortfall, drawing up ideas on a sheet of butcher paper.

Still, Newsom frequently mentions his relationships with Darrell Steinberg and John A. Pérez, the Democratic leaders of the State Senate and Assembly, and has insisted that he will be involved in substantial legislative work.

“I’m not someone that’s going to sit around timidly and passively and bide my time, quite the contrary,” he said in a brief interview last week. “I have a unique skill set and experience as a county mayor, not just a city mayor. That’s a different perspective than we’ve ever seen.”

In Sacramento, Newsom could build a reputation beyond the same-sex marriage issue that has defined him, especially in Southern California.

Sherry Bebitch Jeffe, a senior fellow at the School of Policy, Planning and Development at the University of Southern California, said that when Newsom began campaigning for governor, the only thing most Southern California voters knew about him was his 2008 declaration that San Francisco would perform same-sex marriages “whether you like it or not.”

“That may play well in San Francisco,” she said, “but it has negative connotations across much of the state.”

Jim Brulte, a former Republican leader of the State Senate, said the lieutenant governor’s office would allow Newsom to remake his image statewide.

“This gives him at least four years to build a constituency outside San Francisco,” Brulte said.