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Don Ryan, Associated Press
Eva Varga tallies Oregon ballots at Multnomah County election headquarters in Portland, Ore., Monday, Nov. 3, 2014. Oregon's elections are vote-by-mail or voters can drop off ballots at specified locations.

PORTLAND, Ore. — Oregon's expensive fight over the labeling of genetically engineered food has entered the final round.

An initiative before voters Tuesday would require manufacturers to label genetically engineered packaged foods as "Produced With Genetic Engineering" or "Partially Produced With Genetic Engineering." The change would take effect in 2016.

The measure would not apply to animal feed or food served in restaurants.

If it passes, Measure 92 could make Oregon one of the first states to pass a labeling measure in an election.

Colorado voters also are tackling the issue Tuesday, and the Vermont Legislature approved a labeling bill that's set to take effect in 2016. Scores of countries have GMO labeling laws, including the entire European Union.

Over the past two years, proposals to require GMO labeling have failed in neighboring California and Washington. Oregon voters also have defeated a labeling measure, but that was in 2002, when the issue was less on the public radar.

Earlier this year, voters in two rural Oregon counties approved bans on genetically engineered crops, showing the issue has gained traction outside liberal Portland.

The votes in Jackson and Josephine counties followed the discovery of a patch of GMO wheat in eastern Oregon, a finding that led Japan and South Korea to temporarily suspend imports of the crop.

Though genetically engineered crops are common and no mainstream science has shown they are unsafe, opponents contend GMOs are still experimental and promote the use of pesticides. They say more testing is needed and people have a right to know what's in their food.

Opponents, including some of the world's largest food producers, have raised about $20 million to prevent the labels from appearing on Oregon grocery shelves. Though the labels are not a warning, they fear the words will spook consumers.

The campaign to pass Measure 92 has surpassed $7.5 million in donations.

The anti-labeling campaign spent about $45.6 million in California, compared with $8.7 million spent by supporters. In Washington state, opponents spent $33.3 million, compared with $9.8 million by the pro-labeling groups.