This November, Fresno County leaders are seeking approval of Measure B, a ballot initiative that would renew a one-eighth-cent sales tax for libraries.

The tax, which has been on the books for 14 years, accounts for about half of the county library system's total budget. It pays for books, librarians and library buildings.

With such a large chunk of funding at stake, supporters are redoubling efforts to make sure that tax money doesn't go away.

Campaign signs are popping up on street corners, volunteers have opened an office in northeast Fresno to organize phone banks and even some of the county's most conservative politicians are working to get the word out.

"We need this money to sustain the libraries," said Supervisor Phil Larson, who is urging a yes vote.

Lesser known among county voters is "Plan C." The plan, dubbed C for contingency by chief Librarian Laurel Prysiazny, lays out what will happen should Measure B fail.

The work in progress calls for laying off about 150 of the library system's 292 employees, closing about half the system's 34 branches and possibly reducing hours at libraries that remain open.

Which branches will survive has not been determined.

Of course, Prysiazny is hoping she doesn't have to resort to Plan C.

Library measures have historically done well in California. And Measure B has polled favorably so far.

Still, several hurdles remain. For one, taxes -- which require a two-thirds vote to pass or extend -- are never an easy sell, particularly during tough economic times.

Secondly, Measure B is sharing the ballot with a number of contests, including other taxes, and voters could lose interest as they make their way through the issues.

Supervisor Susan Anderson, a strong advocate for libraries, worries that even the county's second ballot measure may get in the way.

Measure O, which would make it easier for the county to privatize government services, could be viewed as a contradiction to Measure B's support for public libraries, Anderson said: "It could confuse voters. It would have been better for Measure B if it wasn't on there."

Still, Anderson said she believes that most county residents see the importance of libraries and will back the measure.

The campaign for Measure B -- which has raised about $100,000 so far, according to campaign officials -- is using past successes of the library tax to make its case.

Since the measure's passage in 1998, the nearly $150 million raised has not only supported core library services but fueled the expansion and opening of several branches, including the showcase Woodward Park Regional Branch in 2004.

The number of materials checked out since the measure passed, according to library officials, has increased 21/2 times.

Last fiscal year, the sales tax brought in about $13 million of the Fresno County Public Library system's roughly $24 million budget.

While Measure B has no organized opposition, there are critics.

Clovis resident Chloe Foster, who wrote the ballot argument against the measure, said the county should be able to get by without the tax money.

"They may have to cut back," she said. "All government entities and families are having to."