The citizens in Washington state are about to make a decision that could have a big impact across the nation.

They will be voting Tuesday on Initiative 522, which would require labeling of all genetically modified (GM) foods on state supermarket shelves by 2015. If early surveys are any indication, voters there may be about to deliver the food industry a major defeat. Two-thirds of Washingtonians told pollsters last month that they will vote yes on Initiative 522, though Reuters reports that more recent surveys have the gap closing considerably.

Washington, a progressive state that has been a pioneer in legalizing marijuana and same-sex marriage, may become the first in the nation to require that controversial genetically modified foods be labeled.

If so, the food industry fears other states may soon follow suit. A coalition, which includes the Grocery Manufacturers Association and biotech giants like Monsanto, Bayer and DuPont, have poured over $21 million into a TV ad blitz to shoot down the initiative. A similar campaign in the final weeks before last year’s California “Right to Know” referendum, led to its narrow defeat (after earlier polling had shown more than 60 percent of voters there supporting labeling).

The food industry is arguing in its slickly produced spots, featuring farmers and a former state director of agriculture, that creating a new labeling system will be costly, raising grocery bills by as much as $360 per year for a family of four. Food activists counter with a study by economist Joanna Shepherd-Bailey of Emory University that predicts “food prices [are] likely to remain unchanged for consumers.”