After calming down for a little while, the battle over the labeling of foods with genetically modified organisms (GMOs) is heating up at the national level once again, with a new bill in the Senate potentially setting the rules of the road.

The bill, introduced last week by Sen. Pat Roberts and currently sitting in the Senate Agriculture, Nutrition & Forestry Committee, which Roberts chairs, would create a national labeling system for GMOs but would make it voluntary. The bill would effectively make efforts to legislate the issue at the state level, most notably in Vermont, null and void.

The food industry has been supportive of the approach, a version of which passed in the House last year, but industry watchdogs feel the opposite. Among GMO labeling supporters, the bill is derisively known as the “DARK Act,” or the “Deny Americans the Right to Know Act.”

Advocacy organizations such as the Environmental Working Group have called for a simple, mandatory label, without “gimmicks” such as the SmartLabel Initiative introduced by the Grocery Manufacturers Association last year.

“Labeling opponents have also proposed high-tech alternatives that would require consumers to use their smart phones to scan electronic codes on the food packages,” EWG’s vice president of government affairs, Scott Faber, wrote in a Hill op-ed. “But, nine out of 10 consumers not only want mandatory GMO labels—they tell pollsters that they want GMO labels on the package, not high-tech gimmicks. There are plenty of reasons to be skeptical about digital alternatives to on-package disclosures—starting with the fact that many low-income and elderly consumers don’t have smart phones.”

GMA, meanwhile, says that it’s important for a new law to be passed at the federal level before the first state law takes effect, potentially exposing foodmakers to a patchwork of regulations.

“With Vermont’s mandatory labeling going into effect in July and other states considering their own laws, Congress must pass a national food labeling solution that offers farmers, families, and food producers the certainty and access to the affordable and sustainable food supply they deserve,” GMA President and CEO Pamela G. Bailey said in a statement. “Time is running out, and consumers will ultimately pay the price of delay and inaction, as multiple studies have found that state mandatory GMO labeling laws will increase a family’s annual grocery bills by hundreds of dollars.”

The New York Times editorial board, meanwhile, publicly questioned whether Congress should be getting involved in this fight at all, particularly as it seems to be setting up a situation where the Republican-led Congress is stepping into a states-rights issue.

“This is a bad idea that lawmakers and the Obama administration should oppose,” it wrote on Thursday.

The Organic Consumers Association, in a blog post this week, argued on such states-rights grounds.

“Vermont’s law should not be blocked. It was supported by a majority of Vermont citizens and lawmakers,” the association wrote.

The legislative push comes at a time when some manufacturers, sensing consumer trends, are starting to label for GMOs on their own. Campbell Soup Co. announced its plans to begin labeling for GMOs—and threw its support behind mandatory labeling—last month.

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