It may not have bumper sticker potential: “Vote Sanchez! She’s not from the Bay Area!”

But for an instant in her uphill battle for the U.S. Senate, Rep. Loretta Sanchez, an Orange County Democrat, tried appealing to a sentiment that rarely registers in California politics: regional pride.

Campaigning last spring in Southern California, Sanchez described her rival, state Attorney General Kamala Harris, as “from San Francisco.” And when the men she was talking to remarked that California didn’t need yet another Bay Area native holding statewide office, Sanchez pounced. “They control everything,” she said. “So we’re trying to beat them.”

Everything? Not quite.

But there’s no question that as California turns a deeper shade of blue, Bay Area Democrats are ascendant over their compatriots from the Southland.

The Bay Area accounts for nearly one in five Californians, but it’s produced seven of the 10 current statewide officeholders: Sens. Dianne Feinstein and Barbara Boxer, Gov. Jerry Brown, Lt. Gov. Gavin Newsom, Controller Betty Yee, Superintendent of Public Instruction Tom Torlakson and Harris.

By contrast, Southern California, home to nearly 60 percent of the state’s residents, claims just two: Secretary of State Alex Padilla and Treasurer John Chiang, neither of whom faced a viable Bay Area opponent in the 2014 election.

That’s a far cry from 1990, when Southern Californian politicians controlled a majority of statewide offices, including the governor’s office (George Deukmejian) and one U.S. Senate seat (Pete Wilson, who would go on to become governor).

Theories abound about the unprecedented moment of Bay Area electoral dominance. Political observers cite San Francisco’s political machine churning out well-connected political stars, Los Angeles’ celebrity-obsessed local news broadcasts keeping politicians off the airwaves and the Bay Area’s one-sided rivalry with Los Angeles producing more parochial voters up north.

But the Bay Area’s undisputed advantage is that its residents are far more politically engaged, especially compared with Los Angeles.

“We refer to Los Angeles as the black hole of politics,” said Bob Mulholland, a veteran Democratic Party strategist who has knocked on doors all over the state canvassing voters.

“If you ask a voter in Los Angeles, ‘Who’s your Assembly member?’ they’ll say, ‘What’s an Assembly member?’” he said. “But if you ask ‘What’s Lindsay Lohan up to?’ they’ll know all about it.”

Bay Area voters are on the opposite end of the spectrum, said Mulholland, a Chico resident. “If you go door-to-door in San Jose or San Francisco or Oakland, whether it’s rent control or a legislative election, they’ll actually know something.”

And more important, they are far more likely to vote — especially in the low-turnout primary elections that often decide which Democrat ends up on the November ballot.

In the June 2014 primary, Los Angeles County had nearly 1.3 million more registered voters than the Bay Area. But the nine-county region cast nearly 268,000 more votes.

The high turnout here likely lifted Yee, a San Francisco resident, just past then-Assembly Speaker John Pérez, of Los Angeles, into the November runoff for state treasurer in which Yee easily beat Ashley Swearengin, the Republican mayor of Fresno.

Yee won her native San Francisco, where 30 percent of registered voters cast ballots, by 18 percentage points. Turnout was only 17 percent in Los Angeles, which Perez carried by 5 points.

“The joke used to be that you had to be from Los Angeles to get elected because that is where the votes were,” said Richard Schlackman, a veteran San Francisco political strategist. But that has changed over the past two decades, he and other political experts said, in large measure because Bay Area election officials embraced permanent absentee voting and Los Angeles initially resisted it.

“The L.A. County recorder didn’t think they could handle it,” said Douglas Herman, a Los Angeles-based political strategist. “That box on the voter registration form that says, ‘Click here to be a permanent absentee voter’ — it didn’t appear on L.A. forms for years.”

It’s a well-established fact that people who vote by mail are far more likely to participate in elections, especially low-turnout primaries.

Take the June 2014 primary, when 267,989 more votes were cast in the Bay Area than in Los Angeles County. Just under half of Angelenos voted by mail, compared with 77 percent of Bay Area voters. Two decades earlier, in the June 1994 primary, when absentee voting was still rare across the state, the Bay Area’s turnout advantage was just 1,990 votes.

“It doesn’t take long to do the math,” Herman said. “You can see that huge advantage showing itself.” A bill now sitting on Gov. Brown’s desk, however, could eat into the Bay Area’s advantage by ensuring that all voters are mailed a ballot.

The northward shift in power was barely perceptible until late last year, when Boxer, who won her Senate seat as a congresswoman from Marin County 24 years ago, announced her retirement.

Instead of a battle royale for one of the most coveted offices in the state, top Southland Democrats like Rep. Xavier Becerra and former Los Angeles Mayor Antonio Villaraigosa cleared the way for Harris, who rose to prominence as San Francisco’s district attorney. That left Harris to duke it out with Sanchez, a fellow Democrat — but one with far less institutional support.

Sanchez’s chief strategist, Bill Carrick, said she isn’t making the Bay Area’s political dominance a campaign issue. But former state Senate President Pro Tem David Roberti said Sanchez has raised a legitimate point.

“I’m from L.A. It bothers me a little,” Roberti said. “Right now it seems overwhelming.”

Roberti attributes the Bay Area’s ascendancy primarily to the demise of the state Republican Party. He said Democrats are so dominant in the Bay Area that even with a smaller population, its voters essentially pick which Democrats wind up on the November ballot. And those Democrats are almost certain to win because Republicans now make up only 27 percent of California’s registered voters.

To be sure, not every major politician can be put into a geographical box. Harris a couple of years ago moved to Los Angeles to be with her new husband. And Boxer quietly moved to Rancho Mirage near Palm Springs a decade ago — although Roberti said “that hardly makes her a Southern Californian.”

Perhaps no politician better reflects the shift in power across the state than Gov. Jerry Brown. After growing up in San Francisco and going to UC Berkeley, Brown moved to Los Angeles to get his start in politics a half-century ago.

But he returned home to eventually make his comeback as mayor of Oakland. “Where better to re-emerge than a Democratic bastion like Oakland?” remarked Roberti. “There wasn’t a place of corresponding potential for him in Southern California.”

While some Southern California politicians may gripe about Bay Area dominance, Herman said, it doesn’t come up in focus groups that he runs.

And there is little sign that it impacts policy, several former legislators said. Both houses of the Legislature for the first time in recent memory are now led by Los Angeles-based Democrats, and the Southland’s numerical majority means any bill must have some backing from the region, said Ellen Corbett, a former Democratic state senator from Hayward. And Richard Katz, a former assemblyman from Los Angeles, said he had no complaints about his two Bay Area U.S. senators when it comes to showering the region with federal transportation dollars.

“Senators Boxer and Feinstein could not have done a better job for us, no matter where they live,” Katz said.

Even activist Republicans such as Steve Frank, of Simi Valley, said they cared more about policy than geography.

Frank said it’s the Bay Area’s left-wing ideology that counts: “That is what has taken over politics. It’s like a disease, and ‘patient zero’ is San Francisco.”

Indeed, five of the seven Bay Area statewide elected officials either hail from San Francisco or made a name for themselves there.

The city’s compactness has helped foster a culture of grass-roots political engagement and networking that “much more closely resembles Boston or Chicago than Los Angeles or San Diego,” said Dan Schnur, director of the University of Southern California’s Unruh Institute of Politics.

San Francisco also sits at the center of a consolidated Bay Area media market that pays reasonably close attention to local politics.

“The L.A. media market serves half the population of California,” Schnur said. “Most elected officials down here aren’t going to make it on television unless they hold up a 7-Eleven.”