It's the other bond measure on the March 2 ballot: Proposition 55 would authorize $12.3 billion for construction of school buildings to relieve overcrowding and repair existing facilities.

Unlike the more publicized Proposition 57 - a $15 billion bond that would refinance California's accumulated budget debt - supporters say Proposition 55 is an investment in the state's future.

For a growing school district like Elk Grove Unified, which is adding nearly nine students a day and needs to build three to four schools a year to keep pace, Proposition 55 would provide more than $85 million.

With matching funds, district officials believe their share would pay for a new high school and middle school, six to nine new elementary schools, additions to three elementary schools and a high school, and modernization of two high schools.

"Without the money, we would fall short of coping with growth and doing the modernization we need to do," said Elk Grove Superintendent David Gordon.

But opponents like the Howard Jarvis Taxpayers Association, the California Republican Assembly, and state Sen. Rico Oller, R-San Andreas, warn that California should not be taking on more debt during a budget crisis.

They call Proposition 55 ill-conceived and contend the state's school construction policies drive up costs because of prevailing wage and design requirements.

"Bonds are a wasteful way to fund construction because with interest the payout (doubles) the initial amount," said Mike Spence, head of the California Republican Assembly, a grass-roots organization.

Spence said the state should adopt a "pay-as-you-go" approach to school construction. He accused the Legislature of running a "shell game" on the public by overspending and then asking voters to bail out schools.

Kam Kuwata, campaign manager for Proposition 55, concedes it's "difficult" to ask voters to approve a record amount of borrowing in the current atmosphere.

But he and other supporters, including the California Teachers Association, the California Chamber of Commerce and the California Taxpayers Association, are hoping voters will continue to invest in public education.

Two years ago, voters passed a similar $13 billion bond measure, then the largest school construction bond in state history.

Campaign officials decided to split the bond campaign over two elections to make the amounts more palatable to voters, according to David Sanchez, vice president for the California Teachers Association.

The state's largest teachers union has given $3.9 million to the Proposition 55 campaign, more than the other contributors combined.

Their strategy was upended when Gov. Arnold Schwarzenegger put Proposition 57, an even bigger bond, on the ballot as the linchpin of his economic recovery program.

Supporters say California, with its massive economy, can afford both bonds. Schwarzenegger also backs the education bond.

The nonpartisan Legislative Analyst's Office estimates the measure would cost taxpayers about $24 billion over 30 years, including $12.4 billion in interest, or about $823 million annually. The bond principal and interest would be repaid from the state's general fund.

If Proposition 55 fails, it will go on the November ballot for a second vote.

Even if it passes, voters will likely face more school bond decisions.

Based on project needs identified by K-12 and higher-education officials statewide, the legislative analyst estimates there are $21.3 billion in new construction and modernization projects awaiting funding.

With roughly 7.9 million students enrolled in California schools, from kindergarten through college, the state has among the most crowded classrooms in the nation.

Enrollment is increasing, as is the backlog of unmet construction and repair projects.

Nearly 75 percent of California's public schools are at least 25 years old, and many classrooms, restrooms and other facilities are in disrepair.

State Superintendent of Public Instruction Jack O'Connell estimates there is a $120 million backlog of school repair projects awaiting funding from the state.

Of the $12.3 billion in Proposition 55, $10 billion would be allocated to repair, modernize and build K-12 schools - including $2.4 billion for critically crowded schools.

The remainder would go to higher education, including $620 million for University of California projects; $620 million for California State University projects; and $920 million for community college projects.

In addition to Proposition 55, there are more than 50 local school funding measures on the March ballot. These districts are counting on Proposition 55 to help fix schools in their areas.

But Oller, who wrote a ballot argument opposing the measure, contends only wealthier school districts can afford to come up with the matching funds.

At the same time, he believes the provision of the bond measure that sets aside $2.4 billion for "critically overcrowded schools" is weighted in favor of Los Angeles and other urban districts.

Supporters say the provision merely gives these schools more time to apply for the bond funds. Otherwise, suburban districts, which have undeveloped land and face fewer legal battles, would have an unfair advantage.

Sanchez, the CTA vice president, said the bond money would be distributed around the state.

"There's a lot of schools that would be able to take advantage of these bonds," he said, citing the Santa Maria Elementary School District, where he teaches.

"We have two elementary schools near completion, and we're going crazy waiting for this money."

Maria Lopez, a spokeswoman for the Sacramento City Unified School District, said most of the approved projects in the district also are waiting for state funding.

"(At) Genevieve Didion Elementary School, a number of portable classrooms are 20 years old or more and need to be torn down and replaced," said Lopez. "We're also awaiting extensive modernization work at a number of other schools."

But Jon Coupal, president of the Howard Jarvis Taxpayers Association, argues that at this "precarious point we do not think additional debt is appropriate."