Marshall Tuck, a former charter-schools executive who is running for school superintendent in California, is receiving support from donors behind the national charter school movement and the effort to weaken teacher tenure. (Rich Pedroncelli/AP)

Perhaps the most important — and definitely the most expensive — election in California on Tuesday is the down-ballot battle for state school superintendent. The $30 million race has generated three times as much spending as the contest for governor, with money pouring in from across the country.

But the election is not a partisan fight between the two major parties. The combatants — incumbent Tom Torlakson and challenger Marshall Tuck — are both Democrats, and their fight embodies the major divide within the Democratic Party over the best way to educate children.

“These two candidates represent almost the perfect contrast between the two sides in the national debate over public schools,” said Dan Schnur, executive director of the Unruh Institute of Politics at the University of Southern California. “This debate has the potential to divide the Democratic Party just as significantly as immigration and abortion has divided the Republicans in the past.”

Torlakson is heavily backed by the teachers union; Tuck is receiving significant support from well-heeled donors who are behind the national charter-school movement and the effort to weaken teacher tenure.

Going into Election Day, Torlakson led Tuck 32 percent to 29 percent among likely voters polled by the Unruh Institute and the Los Angeles Times. Among all registered voters, Torlakson led Tuck 30 percent to 28 percent. Both splits were within the margin of error.

Tom Torlakson is running for reelection as state schools superintendent in California and is heavily backed by the teachers union. (Rich Pedroncelli/AP)

The candidates and outside groups have spent a total of $30 million, according to state campaign records. Just $10.1 million has been spent in the contest between Gov. Jerry Brown (D) and his GOP challenger, Neel Kashkari.

And that is odd, Schnur said, considering the superintendent job does not wield much power. The state superintendent for public instruction carries out the policies set by the state board of education, which is appointed by the governor.

“But it represents the most high-profile battle between the two preeminent schools of education reform,” Schnur said. “It’s symbolism with a great deal of real-world impact. It will set the tone for the education debate in California going forward.”

Torlakson, 65, was first elected in 2010. Along with Brown, Torlakson has rejected the Obama administration’s push to use standardized test scores to evaluate teachers. He has argued for heavier investment in public schools and says that charter schools serve a role but need greater oversight.

Torlakson is a former high school biology teacher who got active in union politics. After his teaching career, he spent more than a decade serving in the state legislature, winning seats in both the assembly and the state senate.

Tuck, 41, is a former president of Green Dot Public Schools, a chain of Los Angeles charter schools. He also is a former chief executive of the Partnership for Los Angeles Schools, a nonprofit school-turnaround group that operates more than a dozen public schools in that city. Prior to his work in education, Tuck was an executive at a software company and worked for two years in mergers and acquisitions at Salomon Brothers.

His donors include the heirs of Wal-Mart founder Sam Walton; Michael R. Bloomberg, the former mayor of New York; Eli Broad, the housing and insurance mogul; and Laurene Powell Jobs, the widow of Apple founder Steve Jobs. Even some Hollywood stars made a video supporting Tuck.

The differences between the candidates were starkly evident following the June ruling in Vergara v. California , in which a state judge struck down the state’s teacher tenure policies because he found they violated the rights of poor children.

Tuck celebrated the Vergara ruling, while Torlakson slammed it and is seeking an appeal.