In the governor's race, Brown has edged into a narrow lead with support from 46 percent of likely voters, compared with 41 percent for Republican Meg Whitman.
Boxer has support from 48 percent of likely voters as she seeks a fourth term in the Senate, while 40 percent support her Republican challenger, Carly Fiorina. The remaining voters said they were leaning toward one of the candidates in each race or remained undecided.
Brown's surge came the week he began running his first advertisements attacking Whitman. He portrayed her as the Disney character Pinocchio, with her nose growing when she tells a lie.
The state attorney general was running stronger among Hispanic voters than he was in a poll taken earlier in the summer. Hispanics are a traditional Democratic voting bloc that Whitman has sought to woo with Spanish-language television ads and billboards. Brown was favored by 44 percent of likely Hispanic voters in the poll, compared to 26 percent for Whitman.
Both candidates need to have a strong grassroots effort to reach Hispanics, who typically are not persuaded to go to the polls through television advertisements, said Louis DeSipio, chairman of Chicano-Latino Studies at the University of California, Irvine.
"The Democrats have an opportunity with Latinos in 2010," DeSipio said. "If Latinos turn out in large numbers, that will raise the likelihood of a Brown victory."
Hispanics are having a growing influence in California politics but are projected to comprise just 15 percent of voters in the Nov. 2 general election.
Brown, who has sought to appeal to average Californians with his tales of frugality, does well among likely voters who believe he understands their problems better than Whitman, the billionaire former chief executive of eBay. When asked that question, 48 percent of survey respondents pointed to Brown compared to 36 percent for Whitman.
Whitman is seen as the candidate who would do a better job with the economy, with 46 percent of voters responding favorably to her on that issue compared to 36 percent for Brown. Her campaign has revolved around the themes of restoring private-sector jobs and getting the state budget under control.
The candidates are about even when respondents were asked which would do a better job on taxes or has a clear plan for governor. Whitman has sought to portray Brown as a career politician who wants to raise taxes, launching a clever television ad featuring former president Bill Clinton making a similar charge during the 1992 Democratic presidential primary. Meanwhile, Brown said he cut $4 billion in taxes when he was governor from 1975 to 1983, and Clinton has since disputed Whitman's ad.
Brown has said he would not raise taxes without a vote of the people.
When asked which candidate would be better for public education, Brown leads 47 percent to 33 percent among likely voters.
Like Brown, Boxer appeared to benefit from her first statewide advertisement, which began running two days before polling began for the survey.
Likely voters also said Boxer understands their problems and concerns more than the former chief executive of Hewlett-Packard Co., but they were divided over which candidate would do a better job on the economy and taxes. Those are central themes of Fiorina's campaign.
Fiorina has advocated for the extension of all the Bush-era tax cuts, including those for the wealthy, as a way to boost the economy. She has criticized Boxer for supporting the $814 billion economic stimulus package, which she believes has failed to create sufficient private-sector jobs.
Boxer has aligned with President Barack Obama on the issue, favoring an extension of the tax cuts for middle class and lower-income taxpayers but not for the wealthiest Americans. Voters surveyed said they preferred a senator who supports the policies of the president, by 54 percent to 40 percent.
That might not bode well for Fiorina, who often stakes out positions contrary to the president and has said she would vote to repeal the landmark health care reform bill he signed into law earlier this year.
Voters have much more confidence in Boxer's stewardship of the environment, an issue Boxer has consistently worked on during her Senate career. This year, she has been promoting national regulations to reduce greenhouse gas emissions.
Both candidates have catered to their party's base. Among likely voters, 39 percent say Boxer is too politically extreme, while 34 percent share the same opinion of Fiorina.
The poll was conducted by the Democratic firm Greenberg Quinlan Rosner and the Republican firm American Viewpoint.
It surveyed 1,511 registered voters by telephone from Sept. 15 to Sept. 22, and had a sampling error margin of 3.3 percentage points for likely voters and 5.1 percentage points for Hispanic respondents.
