Measure 27 would make Oregon the first state in the nation to require labels on all foods and beverages that contain ingredients made from genetically engineered materials.
Foods without the labels could not be sold in Oregon under the measure.
The measure defines genetically engineered foods as those that are 'grown, manufactured or processed using means or methods that could not occur in nature,' such as foods whose DNA has been altered.
National and international agribusiness giants such as Monsanto Co. have contributed millions to oppose the measure. Measure supporters have raised about $26,000.