In an election year when Oregonians will make weighty decisions on abortion and immigration policy, the ballot measure attracting the most cash has to do with the humble grocery cart.

RELATED: Live Oregon and Washington 2018 midterm election results.

In what amounts to a pre-emptive strike at new taxes on grocery chains — and the farms and factories that supply them — large grocers are dumping millions of dollars into passing Measure 103.

“Keep our groceries tax free!” say ads blanketing the airwaves, plastered to websites, waiting at your grocery store’s check stand. The messages are so pervasive, you might think there’s currently a statewide proposal to slap a tax on your supermarket.

There isn’t.

Instead, Measure 103 would change the Oregon Constitution, prohibiting lawmakers from imposing a new “tax, fee, or other assessment” on the “sale or distribution” of groceries, if one is proposed in the future. In doing so, it would largely freeze in place the tax structure that grocers and their suppliers operate under today.

“There are really only two sides of this measure,” says Joe Gilliam, president of the Northwest Grocery Association, the leading advocate for Measure 103. “Those who want to keep their groceries tax free and those that want to tax groceries and continue to come up with proposals to tax your groceries.”

More On Oregon Ballot Measures: 104 | 105 | 106

In Oregon’s longstanding debate over how to pay for public services, specifically taxing grocery sales isn’t likely to gain any traction. Even states that have a sales tax — a concept Oregonians have repeatedly shot down — typically exempt groceries.

“We don’t have a sales tax on groceries,” says Katherine Driessen, a spokeswoman for advocacy group Our Oregon, which has pushed repeatedly for higher corporate taxes in the state. “Certainly nobody’s proposing one. It’s a complete non-starter.”

Yet Gilliam and his allies argue other recent proposals would have amounted to a tax on groceries. Most prominent is Measure 97, a 2016 ballot proposal to create a new 2.5 percent tax on corporate sales of more than $25 million. Grocers played an outsized role in convincing voters to resoundingly reject that measure, claiming it was a sales tax in disguise.

Measure 103 backers also say proposals for taxes on sugary beverages — including an effort in Multnomah County that was delayed earlier this year — are a looming threat to Oregon grocers. Their proposal would make such taxes impossible.

“Most of the folks on the other side of the measure have kind of brought us to this point,” Gilliam says.

Gilliam argues Measure 103 is a straight-forward way to make sure that food and beverages are kept out of future conversations about how to pay for public services. (The proposal does not cover sales of grocery store staples that aren’t meant for consumption, such as toilet paper. Alcohol, cannabis products and tobacco are also not included, though e-cigarettes aren’t contemplated by the measure.)

But Measure 103’s opponents say it’s far more complicated than that. They say the measure would lock sloppy, confusing language into the state’s constitution, where it will be difficult to fix or remove. And they say the measure could block big grocery chains from paying their fair share for state services in the future.

“The very idea that we would risk putting something legally ambiguous into Oregon’s Constitution just doesn’t make any sense at all,” says Becca Uherbelau, executive director of Our Oregon.

As a chief opponent to Measure 103, Uherbelau helms a coalition that includes unions, dozens of community and advocacy groups and a list of businesses that includes Nike. The same groups are opposing Measure 104, another anti-tax proposal that would make it harder for the Oregon Legislature to raise new revenue.

One of their central arguments against Measure 103: That it’s vague and overly broad.

The measure prohibits new taxes on the “sale or distribution of groceries” and goes on to define those terms in a way intended to capture not just grocery stores, but any entity in the grocery supply chain.

Our Oregon says that definition creates huge complications. An analysis from the group’s attorney suggests the measure would wind up prohibiting taxes on food sales at hospitals and trucking companies that haul groceries and even preempt changes to bottle deposits in Oregon.

It’s not clear those arguments would hold legal weight. The Oregon Department of Justice has said that Measure 103 wouldn’t impact an assessment on hospitals that voters passed in January to fund Medicaid, and wouldn’t affect planned increases to the state’s gas tax for trucking companies that haul groceries. The Oregon Beverage Recycling Cooperative, which facilitates the Oregon Bottle Bill, says deposits would remain untouched.

The measure’s opponents say those opinions won’t be enough to stop lawsuits if Measure 103 passes. Uherbelau believes companies will fight to win protections from taxes under the law.

“The fact that we’re arguing over what it covers and what it doesn’t means there will be industries out there that say, ‘Oh it doesn’t cover me,’” she says. “It’ll cost the state of Oregon and local communities hundreds of millions of dollars to litigate these issues.”

The best example of this confusion involves restaurants.

According to the DOJ, Oregon eateries would be protected from new taxes under the law. Restaurants are even specifically included in the ballot language for the measure, a detail cheered by the Oregon Restaurant and Lodging Association.

“A meal at a restaurant or from take-out is a regular and increasing part of many Oregonians’ busy schedules,” the group said in a voters’ pamphlet statement. “ORLA supports Measure 103 because it will ensure that such meals remain as affordable as possible without unnecessary and burdensome taxation.

Yet Gilliam insists most Oregon restaurants aren’t included. He points out that a provision in the measure singles out businesses regulated by the Oregon Department of Agriculture, U.S. Food and Drug Administration, and several other agencies.

That list includes “take-and-bake” pizza places like Papa Murphy’s, Gilliam says, but not most other restaurants. He can’t say why the DOJ and others have reached different conclusions.

“We sent a request in to the DOJ saying, ‘How did you get to your interpretation?’ And we have never received a response,” Gilliam says.

A DOJ spokeswoman also declined to clear up the matter for OPB, saying the agency’s role in writing ballot language for the measure had ended. But it’s worth noting the Oregon Supreme Court upheld ballot language that listed restaurants among the businesses the measure would protect.

The factions for and against Measure 103 don’t look all that different from the fight over Measure 97 two years ago. And just as with that battle — the state’s most expensive ballot measure campaign — spending is lopsided.

Public sector labor unions have bankrolled much of the more than $670,000 reported raised by the opposition campaign as of Oct. 9.

Large grocery chains like Kroger and Albertsons/Safeway have put more than $4 million into backing Measure 103, between landing the proposal on the ballot and trying to sway voters. The American Beverage Association, a foe of sugary drink taxes, has also contributed $1 million.

Of course, far smaller organizations have also taken positions on the measure.

The Portland-based League of Minority Voters issued a statement in support of Measure 103 in the Oregon voters’ pamphlet. The group’s president, Promise King, says he’s concerned a hypothetical future tax on grocers could shutter grocery stores and impact access to food. He specifically mentioned ethnic groceries some of his group’s constituents rely on.

“For us, it was just a no-brainer that we have to defend access to groceries for people that are elderly,” King said. “This is a fence.”

The anti-Measure 103 campaign has support from some farms, small markets and restaurants that would be shielded by the proposal. It also has an ally in Tax Fairness Oregon, a Portland-based group that promotes progressive changes to the state’s tax code.

Measure 103 “is very poorly written in its definition of what groceries are, and it could include so many different places we collect tax revenue that it’s ridiculous,” says Jody Wiser, the group’s founder. “You’re talking about taking out a huge piece of the economy, and that’s not OK to do that kind of carve out.”

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