In a classroom partitioned out of what was once a media center, Graciela Romo-Gonzales teaches world and United States history to more than 150 high school students each day.

The Pomona Unified School District teacher sees Proposition 55, the $12.3 billion school facilities bond on the March 2 ballot, as one step toward solving a school facilities shortage that has relegated her to teaching for the last 11 years over background noise that seeps through her flimsy partition walls.

"We do the best we can. The guy next door comes over when the video is too loud ... we can hear each other's lectures sometimes, and the kids will say, "We want to go to that class!"' Romo-Gonzales said.

But while opponents of Proposition 55 do not contest the need for more and better California classrooms, they argue there are more financially responsible ways to build them. They also question whether the money would make its way to schools and districts most in need.

"The case hasn't been made for me on Prop. 55," said Pasadena Community College Trustee Geoffrey Baum, who cast the lone dissenting vote last month when the college's trustees voted to endorse the measure.

Baum questioned the timing of the measure, which comes as the state struggles with a structural deficit between the amount of money it takes in and the amount of money it spends.

"There will be times when you have to take a significant long-term capital investment, but I think that right now we're not in a position to be able to take on such a big debt burden, and I'd like to find ways to better manage existing revenue so we can set aside funds for long-term capital improvements," Baum said.

The money from Proposition 55 would be split between branches of education, with $10 billion going to K-12 districts and $2.3 billion shared between the University of California, California State University and community college systems.

In all but "hardship" cases, districts will be required to match 50 percent of the cost of new construction and 40 percent of the cost of modernization.

The measure earmarks $2.44 billion to districts with schools classified as critically overcrowded, and up to $300 million would be available to charter schools.

"It does not go for administration," said Ellen Taylor, action vice president for the League of Women Voters of the Claremont Area, which has endorsed the proposition. "This bond is to be used for things that long-term bonds should be used for."

It is estimated it will cost about $24.7 billion to pay off the principal and interest on the bond over the next 30 years, with payments estimated at about $823 million per year.

In the past 10 years, voters have approved $20.1 billion in state bonds for K-12 school construction, $1.9 billion of which remains, and $5.1 billion in general obligation bonds, all of which has been spent, for higher education capital improvement projects.

The state currently carries $41 billion in bonded debt, with another $21 billion in approved bonds waiting to be sold.

A narrow majority of voters back Proposition 55, a Public Policy Institute of California survey found last month. The survey found 50 percent of likely voters backed the measure, 38 percent opposed it and 12 percent were undecided.