SAN FRANCISCO, Oct 11 (Reuters) - Support among likely California voters for Governor Jerry Brown's tax measure on the November ballot has dipped below 50 percent for the first time as they learn more about it and advertising against it takes a toll, according to survey results released on Thursday.
The survey for the California Business Roundtable and Pepperdine University's School of Public Policy found 49.5 percent of likely voters supporting the measure, compared with 57.5 percent who said they backed it when surveyed in late September.
The latest survey found 41.7 percent of likely voters opposing the measure and 8.8 percent unsure of how they will vote on it, compared with 35.3 percent who opposed it and 7.2 percent who said they were uncertain in the previous survey for the business group and school.
Advertising against the measure has weakened support for it along with increased awareness of its specifics, said Jeff Harrelson, a partner with M4 Strategies, the firm that conducted the online surveys.
"Voters are paying attention and they're seeing the advertising, specifically the 'no' advertising, which was slow to get up and running," Harrelson said.
The measure, Proposition 30, would raise California's sales tax along with personal income tax rates on the wealthy.
If voters reject the measure, the state government may impose spending cuts that would strike hard at education programs to maintain a balanced budget.
In addition to preventing cuts in the short term, the measure would raise revenue to bolster the state's general fund in future years. The measure would raise about $6 billion annually.
Brown's measure faces competition from another tax measure advanced by a wealthy Los Angeles civil rights attorney.
That measure, Proposition 38, would raise personal income tax rates on annual earnings on all but the poorest Californians to raise money for school spending and early childhood programs and to repay state debt.
Opposition to Proposition 38 has increased since late last month, according to the latest survey for the California Business Roundtable and Pepperdine University's School of Public Policy.
The survey found 45.9 percent of likely voters opposing the measure, up from 43.1 percent in late September. Support for the measure is down, with 41.9 percent in favor compared with 44.9 percent late last month. Just over 12 percent of voters are uncertain about the measure, little changed from late last month.
(Reporting By Jim Christie; Editing by Richard Chang)
Keywords: CALIFORNIA TAX/MEASURE