The two leading candidates for California’s top K-12 spot in the June 3 primary both identify as Democrats in a technically non-partisan race. But the campaign between incumbent Superintendent of Public Instruction Tom Torlakson and challenger Marshall Tuck has each camp slamming the other’s candidate as a creature of competing education power blocs. The Vergara v. California educational-equity trial also highlights this divide. In that pending court case, the plaintiffs have argued that schools retain poor-quality teachers and grant tenure to unproven ones at the expense of students, a charge that unions in the state say ignores the importance of the current laws to a high-quality teaching workforce. Mr. Torlakson, along with the two major teachers’ unions in the state, are defendants in the case, while Mr. Tuck sides with the plaintiffs. Despite the heated campaign, the state superintendent’s post actually has somewhat limited influence compared with other leaders in state government, said David Plank, the executive director of the Policy Analysis for California Education, a research group run jointly by Stanford University, the University of California, Berkeley, and the University of Southern California. Several major policy changes recently have primarily been overseen by Gov. Jerry Brown, a Democrat, and state Board of Education President Michael W. Kirst, according to Mr. Plank. “There’s no lever that belongs to him,” Mr. Plank said of the superintendent’s job. “The power resides elsewhere.”