A school bus arrives at a school in Los Angeles in December 2015. (Ringo Chiu/AFP/Getty Images)

A revolution is coming to the nation’s second-biggest school system, with a pro-charter majority set to take over the governing board of the Los Angeles Unified School District.

Backed by billionaire charter interests and fiercely opposed by teachers unions, the two winners of last month’s bruising election — said to be the most expensive school board race in U.S. history — will take office in July.

Nick Melvoin, 31, and Kelly Gonez, 28, will join two other charter-friendly members on a seven-member board that oversees a system with 1,300 schools, 735,000 students and major academic and fiscal challenges.

L.A. Unified is already home to a significant concentration of charter schools, which are publicly funded, privately managed and seldom unionized. The district counts more than 107,000 students enrolled in independent charter schools, according to a school system fact sheet. That works out to about 16 percent of its non-adult enrollment.

The question now is whether the election will spur the board to authorize even more charters. The winners insist their aim is more about fresh ideas and openness to change.

“I’m school-model agnostic,” said Melvoin, though he added: “When you have more charters in L.A. than anywhere else in the country, it’s an indictment of a failed status quo.”

The rise of the charter movement here coincides with President Trump’s push to use “school choice” to disrupt traditional public school systems.

Unions around the country have sought to take advantage of that dynamic.

In the run-up to the May 16 board election, the union United Teachers Los Angeles issued news releases that lumped the charter-backed candidates and wealthy donors together with the Trump administration.

But the politics of education reform are complex.

Melvoin and Gonez, both Democrats, were endorsed by Arne Duncan, President Barack Obama’s first education secretary. Melvoin, an attorney and former middle-school teacher, campaigned last year for Democratic presidential candidate Hillary Clinton; Gonez, a seventh-grade science teacher, worked for two years as an education policy adviser for the Obama administration.

“I am very strongly against Donald Trump and everything that he stands for,” Gonez said. “For me as a Latina, as a daughter of an immigrant, and a teacher, to be associated in that way with Trump and [Education Secretary Betsy] DeVos was very upsetting.”

Both newly elected trustees say they oppose taxpayer voucher programs that help students attend private schools — a key initiative for Trump and DeVos.

Still, Los Angeles is becoming a crucial laboratory for testing whether market-oriented reform will help or hurt public education, said Pedro Noguera, an education professor at UCLA.

“The campaign didn’t provide any clear indications of what we have to look forward to,” Noguera said. “This is a whole new world we’re entering.”

Charter advocates have long been influential in Southern California. But Steve Zimmer, the two-term incumbent whom Melvoin ousted, said this is the first time a successful pro-charter takeover has been “explicit and electoral” in Los Angeles.

The school board contest here featured record spending, national endorsements and political mudslinging.

All told, the race drew nearly $15 million in contributions, according to the Los Angeles Times. Teachers unions and affiliated political action committees spent millions to back Zimmer and Imelda Padilla, who ran against Melvoin and Gonez, respectively. But charter proponents appeared to nearly double the union spending.

Among the deep-pocketed charter advocates were Netflix founder Reed Hastings, Gap founder Doris Fisher and the Arkansas-based Walton Family Foundation, which was created by the founders of Walmart and has spent hundreds of millions of dollars to expand charter schools nationwide.

Also, real estate and insurance tycoon Eli Broad gave $450,000 to an advocacy group that backed the pro-charter candidates.

“They bought the election,” said Eric Heins, president of the California Teachers Association. “These billionaires are subverting our public schools.”

The battle drew national attention. Sen. Bernie Sanders (I-Vt.) championed the union’s picks and attempted to tie the pro-charter candidates to the “Trump/DeVos agenda.”

“Billionaires should not make a profit off of public school children,” Sanders said in a statement trumpeted by the teachers union.

In another sign of the intensity of the conflict, the Parent Teacher Alliance — a PAC supported by the California Charter Schools Association — sent out mailers that superimposed the face of Zimmer in the gunner’s hatch of a tank in an effort to portray him as a crazed military enthusiast. (Zimmer has never been in the military.)

“I’m not the first person to have had a viciously negative campaign waged against them,” Zimmer said. “But I’m not sure anything quite like this has been done. Certainly not in a school board race.”

Elsewhere in California, wealthy pro-charter interests have ratcheted up spending.

In the Oakland Unified School District, former New York mayor Michael Bloomberg donated $300,000 to a committee that supported three charter-friendly school board candidates in November. (Two won.) Silicon Valley investor Arthur Rock and the late T. Gary Rogers — longtime chief executive of the Dreyer’s ice cream company, who died in May — each chipped in an additional $100,000.

Last fall, pro-charter PACs — again bankrolled by the likes of Hastings, Fisher, the Waltons, Rock, Bloomberg and others — helped steer $17 million to charter-friendly candidates for state legislative races.

In 2014, the contest for state superintendent of public instruction proved three times as expensive as the governor’s race. In the pro-charter corner was Marshall Tuck, a former president of a large network of charter schools. His big-money backing was not enough to defeat the union favorite, Tom Torlakson. Tuck has announced he wants to run again in 2018.

“Folks want to get behind people with newer ideas that are about big change,” Tuck said.

But fresh ideas can be hard to implement when there is bad blood, warned Michael Druckman, executive chair of Schools That Can, a New York-based nonprofit organization serving urban schools nationwide.

“The fact that the elections became a ‘last-stand’ between the district and charter schools leaves such a hostile taste in L.A. that I worry whether true progress can be made,” he said in an email.