SAN FRANCISCO (CBS 5) — The effects of President Barack Obama’s falter in the first debate with Mitt Romney are not just being felt in battleground states, according to KPIX-TV CBS 5′s latest tracking poll of California which shows Romney slicing eight points off Obama’s lead.

Obama had led by 22 points in the CBS 5 tracking poll released four weeks ago. Obama now leads by only 14 points, an 8-point improvement for Romney. At the same time, the poll found U.S. Sen. Dianne Feinstein’s support for her re-election bid remained largely unchanged, month-on-month, suggesting that the erosion in Democratic support is not across-the-board, but contained to Obama. Unclear is whether the Obama erosion is fleeting or long-lasting.

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The poll data released Wednesday showed Obama 53%, Romney 39%, in California. Obama carried the Golden State by 24 points in 2008, so the poll found Obama is now running 10 points weaker than he ran 4 years ago. Among Independents, Obama led by 14 in September, but now trails by 9 in October, a 23-point right turn among the most coveted voters. One explanation, based on the poll data: The number of Romney supporters who said they were voting “for Mitt Romney” as opposed to “against Barack Obama” is way up, month over month.

In the U.S. Senate race, the poll showed Feinstein 54%, Republican Elizabeth Emken 35%. That’s largely unchanged from CBS 5′s last measurement, when Emken trailed incumbent Feinstein by 18 points.

On Proposition 30, the poll showed the issue to be a toss-up at this point. Among the most committed likely voters – those who said they “strongly support” or “strongly oppose” the measure, No narrowly leads Yes 38% to 33% with 29% uncretain. Among the larger group of likely voters, including those with soft support, Yes narrowly leads No 45% to 39% with 16% undecided.

On Proposition 34, which would repeal the death penalty, 32% were certain to vote Yes, 48% were certain to vote No, unchanged from a month ago. Whites, a majority of pro-life voters, and a majority of voters in Greater Los Angeles area and the Central Valley opposed the repeal. Only the Bay Area and liberals supported the repeal.

On Proposition 36, which would revise the 3-strikes law, 44% were certain to vote Yes, 22% were certain to vote No, also unchanged from a month ago. Hispanics, blacks, Democrats, and liberals disproportionately supported the measure. Republicans, conservatives and Asians disproportionately opposed it.

On Proposition 37, about the labeling on genetically modified food, 39% were certain to vote Yes, 30% were certain to vote No, and 31% were uncertain. This marked a significant change from a month ago, when the measure was supported 51% to 16%. Republicans had supported the measure by 29 points, but now oppose the measure by 7 points — a 36-point swing to No. Men had supported the measure by 35 points, but now support by just 2 points — a 33-point swing to No.

The CBS 5 poll was conducted by the firm SurveyUSA which interviewed 539 likely California voters from 10/07/12 through 10/09/12. The poll has a margin of error, depending on the question asked, of plus or minus 3.9% to 4.3%.

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