For a generation, school bonds have been more or less a “slam dunk” in California. Locally and statewide, voters consistently have supported borrowing to build and maintain classrooms.

Not this election. As the state slowly tallies the returns from Super Tuesday, the numbers are painting a decidedly unfamiliar picture: Proposition 13, the sweeping $15 billion bond for school construction, was trailing late 48 hours after the March 3 election with only 44.6 percent approval. It threatened to become the first state bond measure rejected by voters in nearly three decades.

With roughly 3.5 million votes still to be counted, the tally could take weeks to become conclusive, and updated returns have shown Prop. 13 gaining, slightly. (Early returns tend to skew conservative in California, and many Democrats voted at the last minute, waiting to see whether their chosen presidential nominees would drop out.)

But at the moment, Prop. 13 needs at least a number of outstanding votes for passage.

What happened?

Observers and advocates cite a confluence of potential factors, from possible “bond fatigue” at the local level to – on the statewide measure – a befuddling name.

Confusion: The friend of the ‘no’ vote

On paper, Proposition 13, which would have raised $15 billion from general obligation bonds for preschools, K-12 schools, community colleges and state universities, had advantages aplenty. It was referred to the ballot by the Legislature. It enjoyed widespread support from state officials including Gov. Gavin Newsom. It had no organized opposition, and it was the only statewide measure on the Super Tuesday ballot competing for voters’ attention.

But the measure’s proponents say voters appeared to have confused it with the 1978 property tax cut or perhaps with the push to adjust the terms of that earlier measure with changes to commercial property taxation on the November ballot.

That presented an opening to philosophical opponents, such as the Howard Jarvis Taxpayers Association, which likened the measure to a tax increase. They pointed out language in the bond that would have increased debt limits for local districts, essentially allowing them to put larger school bonds on local ballots with potentially higher costs for local taxpayers.

“The old adage that confusion is the friend of the ‘no’ vote—it was never better illustrated than this election on this ballot measure,” said Kevin Gordon, a Prop. 13 supporter and president of Sacramento-based Capitol Advisors Group.

The author of the Prop. 13 legislation, Democratic Assemblyman Patrick O’Donnell of Long Beach, said he plans to introduce a bill that would formally retire the number 13 for future ballot measures.

O’Donnell said that it was too soon to discuss next steps should Prop. 13 fail, but expressed confidence that the measure would have fared much better had it been assigned a different number. A quirk in state law requiring sequential numbering of ballot measures led to its name.

“I think the overriding challenge to this bond measure was the fact that it was named Proposition 13, and that generated a lot of confusion,” O’Donnell said. “Traditionally, voters in the state of California have supported school bonds because they recognize the need to upgrade school facilities across our state.”

Some also cited an apparent failure to effectively communicate the state measure’s importance, as well as some exhaustion from local voters who, in the aggregate, have been asked to decide on hundreds of local school bonds since 2016 totaling tens of billions of dollars, on top of other measures competing with public education.

“I think this [statewide] bond measure could’ve passed, but there was hardly any communication about the need for it to the average voter,” Larry Tramutola, a Bay Area political strategist who has worked on school-related issues for three decades.

Tramutola cautioned against broad-brush conclusions on disparate local measures, but called Tuesday’s apparent rejection rate “staggering.”

Susan Shelley, vice president of communications for Howard Jarvis, said the state bond’s potential failure represents cynicism from voters “that more money is needed when the (state) budget is at record levels.”

“I think voters are very concerned about higher taxes, and the cost of living in California generally, so they’re more sensitive to proposals that will raise the cost of living than perhaps they were in earlier elections,” Shelley said of provisions in the measure to raise local districts’ debt limits.

Polling done by the Public Policy Institute of California leading up to the March 3 primary showed just 51 percent of voters planned to support the statewide measure. In hindsight, the poll also included this notable statistic: Fewer than half of respondents who planned to cast a “yes” or “no” vote told pollsters that the fate of Prop. 13 was important to them.

“With Prop. 13, this really may be a case in which the proponents didn’t make the case to the voters that this is important, essential and is going to be something that impacts schools in their local area,” said PPIC president Mark Baldassare.

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