Five months before Election Day, public support for Gov. Jerry Brown's effort to raise taxes hangs precariously above 50 percent, with confidence in Brown slipping.

A new Field Poll shows 52 percent of registered voters support Brown's initiative to raise the state sales tax and income taxes on California's highest earners, compared to 35 percent opposed.

The tenuous level of support reflects a six percentage point drop from February, before Brown combined his initiative with a more popular measure proposed by the California Federation of Teachers.

The poll, released today, is Field's first measure of public opinion on the matter since the Brown-CFT merger.

"They still have a lead," poll director Mark DiCamillo said, "but there's not a lot of margin there."

Brown has labored unsuccessfully since taking office to raise taxes to help address the state's persistent budget deficits. His November ballot measure is at the center of his agenda this year.

The poll comes amid growing dissatisfaction with Brown's handling of California's now-$15.7 billion deficit. His public approval rating has slipped to 43 percent.

"This is a pretty serious matter for him because he's trying to win the confidence of the public so they'll pass his tax initiative in the fall," DiCamillo said. "These are kind of ominous warning signals."

Still, Brown's tax initiative is faring better than a competing measure backed by civil rights lawyer Molly Munger and the California State PTA.

Registered voters are about evenly divided on Munger's measure, according to the poll, 42 percent in favor to 43 percent opposed.

The poll's release follows a disappointing election for Democrats and their liberal allies Tuesday. Voters in San Jose and San Diego approved ballot measures to reduce pension benefits for city workers, and a proposition to raise the state's tobacco tax was narrowly losing Friday in a race that was still too close to call.

Brown called the pension votes a "powerful wake-up call." The governor's ability to enact pension changes in state government is considered significant to his ability to persuade voters of his commitment to containing costs. The Legislature is expected to take up his pension proposal this summer.

Jon Fleischman, a conservative blogger and former state Republican Party executive director, said the results of Tuesday's election suggest voters are weary of tax increases and frustrated with public employee benefits.

Furthermore, he said, the Howard Jarvis Taxpayers Association and other anti-tax groups will spend millions of dollars ahead of the November election "explaining how we have some of the highest rates of taxes in the country."

The Tuesday election was not without any positive signs for Brown.

In cities throughout the state, 55 of 87 local bond and tax measures passed, according to an analysis by Michael Coleman, a municipal finance expert. Sales tax measures were adopted in eight of the nine cities in which they were proposed.

Local tax increases are typically easier to pass than statewide measures, but Coleman said Brown's tax campaign will likely resemble a local revenue campaign more closely than any previous statewide tax effort has. The tax initiative is tied to billions of dollars in service reductions that will be required if the initiative is defeated, and school districts and other local agencies throughout the state are likely to heavily publicize that potential.

Once a state budget including so-called "trigger cuts" is adopted this summer, Coleman said, "all of those agencies are going to have to then translate what that means for their budgets," doing so in community meetings.

"That's much more like these local measures, where people can really see the consequences of their 'yes' or 'no' vote," Coleman said.

Turnout in November is expected to be far higher and more Democratic than on Tuesday, assisting Brown.

Democrats support Brown's tax proposal by a 3-to-1 ratio, and nonpartisan voters favor it 54 percent to 33 percent, according to the poll.

Republicans oppose the measure 55 percent to 30 percent, according to the poll.

Aisha Wahlstrom was among those contacted by Field. The 50-year-old preschool teacher from Sacramento said she will "definitely" support Brown's measure.

"I believe in order to make the economy work, there must be income, revenue coming in from somewhere," she said."

Of the governor himself, Wahlstrom said, "In light of the situation and the economy, I think he's doing good, I think he's doing the best he could."

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