Support for Proposition 37 is slipping, poll finds SACRAMENTO - An advertising blitz against Proposition 37 has slashed support for the genetically engineered food labeling initiative on next month's ballot and may endanger its prospects for voter approval, a new poll shows. Proposition 37, which once was ahead statewide by more than a 2-1 margin, still leads 48.3% to 40.2% in the poll released Thursday by the Pepperdine University School of Public Policy and the California Business Roundtable. Undecided voters accounted for 11.5%. But with 3 1/2 weeks left to go before the Nov. 6 election, pollsters now foresee a tightening race, as opponents continued a media blitz financed by $35 million in campaign contributions. "This is a great example of the power of advertising," said pollster Chris Condon of M4 Strategies, which conducted the online survey of 830 likely voters from Sunday to Wednesday. Participants were asked to read the official ballot description and pro and con arguments before responding. The new poll results marked a big change from previous polls that showed broad support for the measure, with some showing backing in the high 60% range. The poll took place just as a pair of televised anti-Proposition 37 spots hit the air. "A lot of money has been poured into the No side, and the effect has been dramatic," Condon said. "It's down 19 points" since the previous biweekly poll. Both sides of the Proposition 37 battle reacted predictably to the latest sounding. The Yes campaign has been hurt by "10 days of incessant, pounding lies" on television, said spokeswoman Stacy Malkan, "but in the end, Californians will value knowing what's in their food, and we're confident they will vote yes on Proposition 37." At the No on 37 campaign, spokeswoman Kathy Fairbanks said greater skepticism shown in the poll was the result of a combination of television advertising, news stories and newspaper editorials opposed to the measure. "The more people learn about Proposition 37, the less they like it," she said. What people don't like, Fairbanks said, are the many exemptions in the initiative. Although supporters suggest that the exceptions demonstrate that Proposition 37 is carefully focused, opponents have seized on the exemptions as evidence that the requirements are confusing and contradictory. Under the measure, most dairy products and alcoholic beverages, for instance, are exempt - even though corn that's been genetically modified in a lab frequently is fed to cows and other animals. The same kind of genetically engineered corn often goes into beer, bourbon whiskey and other liquors. About 90% of all corn, soybeans and sugar beets grown in the United States is genetically engineered. Fresh meat, eggs, restaurant meals and even bake-sale brownies also would get a free pass. The exceptions have made for some stark contrasts, exploited by the opponents. Some soy milk, made from genetically engineered soybeans, would be labeled; cows milk would not. Dog food, processed and canned, would be labeled; fresh meat would not. The exemptions are highlighted in a No campaign ad featuring Henry I. Miller, identified as a medical doctor, research fellow at the conservative Hoover Institution think tank at Stanford University and founding director of the U.S. Food and Drug Administration's Office of Biotechnology. Miller singles out a variety of food products - some covered by the initiative and some exempt. The initiative is "arbitrary and completely illogical," he says in the ad, and the exemptions "seem to have been chosen on the basis of special interests." In a backup memo, the No campaign states, "there doesn't seem to be any logical reason why alcoholic beverages should be excluded from the measure's labeling requirement other than to protect the industry's interests or to avoid creating a powerful opponent." Proposition 37 supporters call the exemptions "common sense" that make compliance easy. The ballot measure, they say, is just a first step toward giving consumers "the right to know" what's in the food they buy in stores. Both the alcoholic beverage and restaurant industries confirmed that they had not sought any special exemptions for their businesses. Alcoholic beverages already are regulated by a large body of both federal and state law, Malkan said , and including them in Proposition 37 could violate a California law that requires an initiative to deal with only one subject.