(CNN) – A new survey indicates that the Democrats have slight advantages in the California battles for senator and governor.
According to a CNN/Time/Opinion Research Corporation poll released Wednesday, 50 percent of likely voters in the Golden State say they support Democratic Sen. Barbara Boxer, with 45 percent backing Republican challenger Carly Fiorina and four percent undecided or backing a different candidate. Boxer's five point margin is within the survey's sampling error and is down from a nine point advantage in CNN/Time polling from last month.
Full results (pdf)
Most other polls released over the past two weeks also indicate the three term senator holding a single digit advantage over Fiorina, the former Hewlett Packard CEO.
According to the CNN/Time survey, Boxer leads 90 to 6 percent among Democrats while Fiorina leads 97 to 3 percent among Republicans and holds a 49 to 41 percent advantage over Boxer among independent voters.
"Boxer racks up big margins in Los Angeles County and her home territory in the Bay Area," says CNN Polling Director Keating Holland. "Fiorina has an edge in the rest of Southern California and in the Central Valley. The factor that may put Boxer over the top is her 12-point lead among women."
In a sign that enthusiasm for voting appears to be on the Republican side, when expanded from those likely to vote to the larger sample of all registered voters, Boxer's five point advantage jumps to a 16 point lead.
According to the poll, California Attorney General and Democratic gubernatorial nominee Jerry Brown holds a seven point lead over Meg Whitman, the Republican nominee. Fifty-one percent of likely voters say they support Brown with 44 percent saying they back Whitman, the former eBay CEO Meg Whitman and a billionaire who's contributed more than $120 million of her own money on her bid for governor.
Brown's seven point advantage is at the edge of the poll's sampling error and compares to a nine point lead in late September. Most other surveys out in the past two weeks indicate a large single digit margin for Brown, who served two terms as California governor in the late 1970's and early 1980's.
According to the CNN/Time poll, Brown leads 88 to 8 percent among Democrats while Whitman leads 93 to 5 percent among Republicans and holds a 48 to 45 percent margin among independent voters.
"Geographically, Brown has the same strengths and weaknesses as Boxer - a strong showing in L.A. and the Bay Area, and a deficit in Southern California and the Central Valley," says Holland. "And despite the fact that Brown is running against a woman, he appears to be doing slightly better among female voters than Boxer, with a 14-point margin in that key group."
Brown's seven point advantage among likely voters jumps to a 56 to 38 percent lead among the larger sampling of registered voters.
The poll indicates that by a 53 to 45 percent margin, likely voters are opposed to California's proposition to legalize marijuana.
"Legalizing marijuana has opened a big generation gap in the Golden State," says Holland. "Nearly six in ten voters under the age of 50 support Proposition 19 while six in ten older voters oppose it. Among senior citizens, support drops to just 33 percent."
Proponents of Prop 19 say it would generate much needed revenue and cut drug enforcement costs. The California Attorney General's office estimated that the measure has the potential to bring in hundreds of millions of dollars annually in taxes and fees, while saving the state tens of millions of dollars annually on costs related to incarceration and supervision of marijuana offenders.
President Barack Obama campaigned for Boxer and Brown last week. The poll indicates that 48 percent of likely voters approve of the job Obama's doing as president, with 47 percent disapproving. Among all adults, Obama's approval rating jumps to 54 percent, with 37 percent saying they disapprove of how he's handling his duties.
The CNN/Time/Opinion Research Corporation poll was conducted October 20-26, with 1,527 adults in California questioned by telephone, including 1,329 registered voters and 888 likely voters. The survey's overall sampling error is plus or minus 2.5 percentage points, with a sampling error of plus or minus 3.5 percentage points for likely voters.
– CNN Deputy Political Director Paul Steinhauser contributed to this report
Follow Paul Steinhauser on Twitter: @PsteinhauserCNN