With an unprecedented surge of cash from charter schools and their high-tech backers, normally low-profile school board campaigns have morphed into big-bucks contests to elect charter-friendly candidates and defeat their challengers.

The six-figure spending by independent committees highlights the muscle of charter proponents in Santa Clara County, where the county Board of Education is rapidly approving charter schools that compete for students and funding with established public schools.

The most aggressive campaign appears to be aimed at Anna Song, who is running for her fourth term on the county Board of Education.

The Santa Clara County Schools Political Action Committee has raised nearly $200,000 from Jan. 1 through Oct. 20, and financed auto-dial calls plus four mailers slamming Song and three supporting her challenger, trustee David Neighbors.

“It’s an outrageous amount of money to take out one school board member,” said Song, who’s running for a seat that represents areas served by the Santa Clara, Milpitas and the Berryessa school districts.

Neighbors, who has benefited from $76,000 worth of PAC mailers and auto-calls for his candidacy and against Song, said about the PAC, “I don’t know much about it.”

Created at the suggestion of the California Charter Schools Association, the PAC is run by Santa Clara County political consultants Jay Rosenthal and Jude Barry.

Through Oct. 20, Neighbors raised $23,539 for his campaign. Song raised $6,525

The PAC is also sending mailers to re-elect Grace Mah, who’s running for the county school board to represent areas within the Palo Alto, Mountain View, Los Altos and Sunnyvale school districts. Her opponent, Dave Cortright, is an outspoken opponent of Bullis Charter School in Los Altos.

The PAC dwarfs spending in county school board elections, where serious candidates typically have spent closer to $30,000. “What they’re doing could be very significant,” said Terry Christensen, professor emeritus at San Jose State and a specialist in state and local politics. Because so little is typically spent in a county school board race he said, “it wouldn’t take much to have an influence.”

Among the big donations to the PACs are $75,000 from the California Charter Schools Association Advocates; $50,000 from Netflix CEO Reed Hastings; $50,000 from Gap heir John J. Fisher; $40,000 from Emerson Collective, the nonprofit run by Steve Jobs’ widow Laurene Powell Jobs; and $10,000 from Rocketship charter schools board member Timothy Ranzetta.

Those reached, including Jobs’ spokeswoman Candace Pugatch, declined to comment on their contributions.

The charter school PACs serve as a new counterweight to unions and construction companies that have dominated big giving in local school board races.

Another political action committee, Parents for Great Schools, has raised $41,000 and spent at least $17,000 promoting Magdalena Carrasco for a seat on the East Side Union High School district board. As of Tuesday afternoon, Carrasco had not reported all the PAC contributions on disclosure forms, although she did list $15,250 in other contributions, many from Southern California interests.

Carrasco did not return calls seeking comment.

In addition, the committee is supporting Leland Lowe and Karen Martinez, challengers for the Alum Rock School District board.

Parents for Great Schools also received $10,000 from Jobs’ Emerson Collective. In addition, it took in $15,000 from the California Charter Schools Association Advocates, $5,000 from Ranzetta and $5,000 from philanthropist Carmen Castellano of Saratoga. Smaller contributions came from ex-San Jose Mayor Susan Hammer, PACT Executive Director Matt Hammer, Silicon Valley Leadership Group President Carl Guardino and Rocketship land-use consultant Erik Schoennauer.

Carrasco is one of two challengers seeking to oust two incumbents on the East Side board. Fellow newcomer Thelma Boac, a retired East Side principal, has reported raising $13,300 for the campaign. Incumbent Lan Nguyen hadn’t filed a report by last week’s deadline but said he’s raised about $21,000. And incumbent Patricia Martinez-Roach reported carrying over $84,543 from previous campaigns.

The spending outpaces expenses in two races in San Jose Unified’s two district elections. Paul Murphy, Sandra Engel and Teresa Castellanos have raised slightly less than $10,000 each. Candidate Cathy Davis failed to submit contribution reports.

“It’s unprecedented that so much money is coming into this race against people who are more measured with their approach to charter schools,” said Cortright, who is self-funding his campaign and plans to spend about $1,000.

Had donors given money directly to support high-performing schools, they would have had a more beneficial impact, Song said.

While Song voted against Rocketship Education’s application to open 20 charter schools in the county, Mah voted against Bullis Charter School’s renewal. Rosenthal said that the endorsements are “based on the totality of board votes” and the candidates’ temperament.

Both Song and Cortright deny that they are anti-charter. Ironically, the mailers slam Song not for her charter votes, but for the board’s lavish contracts with current Superintendent Xavier De La Torre and former Superintendent Charles Weis — who might saddle the County Office of Education with an underwater mortgage on his luxury condo. But Song has been among Weis’ detractors. And the mailers praise Mah, who has been one of Weis’ staunchest supporters.

Contact Sharon Noguchi at 408-271-3775. Follow her at Twitter.com/NoguchiOnK12.