A bill that was to be introduced March 25 in the U.S. House of Representatives includes a provision for national, voluntary non-G.M.O. labeling of products, as opposed to mandatory G.M.O. labeling. Under the bill the U.S. Department of Agriculture, which already runs the National Organic Program, would accredit the certification process for voluntary non-G.M.O. labeling.

The bill’s supporters, including industry groups, and the bill’s opponents, including those who favor mandatory bioengineered/G.M.O. labeling laws, disagreed about how the bill would affect consumers’ understanding of labels.

“The potential for a 50-state patchwork of varying label standards would increase costs for producers and translate into higher prices for consumers to the tune of more than $500 per year for the average family,” said Representative G.K. Butterfield of North Carolina. “This bill would provide clear rules for producers and certainly for consumers at the grocery store checkout lane.”

Mr. Butterfield and Representative Mike Pompeo of Kansas were to reintroduce the Safe and Accurate Food Labeling Act of 2015, which preserves and affirms the Food and Drug Administration’s role in food safety, Mr. Pompeo said. While Mr. Pompeo originally introduced the bill in 2014, the reintroduction contains the provision for non-G.M.O. labeling.

“We took the positive feedback we received after our hearing in December (2014) and have been meeting with key stakeholders to ensure this is the right policy for both producers and consumers,” Mr. Pompeo said. “Our goal for this legislation remains to provide clarity and transparency in food labeling, support innovation and keep food affordable.”

Pamela G. Bailey, president and chief executive officer of the Washington-based Grocery Manufacturers Association, urged Congress to pass the bill this year.

“No matter where they live or shop, all Americans deserve to have access to consistent, understandable information about the food they are eating, and this federal legislation would eliminate consumer uncertainty created by a state-by-state patchwork of labeling laws, advance food safety, inform consumers and provide consistency in labeling,” she said.

The Washington-based Center for Food Safety, however, said critics of the bill call it the DARK Act (Deny Americans the Right to Know Act). The Center for Food Safety said the bill may confuse consumers. When consumers see products voluntarily labeled as non-G.M.O., they may believe all products not bearing the label are bioengineered, even when some are not.

The Center for Food Safety added that besides preempting the rights of states to pass their own laws regarding bioengineered food labeling, the measure would limit the authority of the F.D.A. to compel labeling, codify the current voluntary labeling standard and create a pathway that would allow food companies to label bioengineered food “natural.”

“This bill is simply not the solution Americans are looking for,” said Andrew Kimbrell, executive director at the Center for Food Safety. “An overwhelming majority of American consumers want to know if their food has been produced using genetic engineering. That is their right, and they will not relent until Congress or the F.D.A. heed their call.”

The Center for Food Safety instead favors the Genetically Engineered Food Right-to-Know Act introduced Feb. 12 by Senator Barbara Boxer of California and Representative Peter DeFazio of Oregon. The bill would require the F.D.A. to label bioengineered foods so that consumers can make informed choices, according to the Center for Food Safety.

The Center for Food Safety cited a report conducted on behalf of the Consumers Union. The report showed the median increased cost of mandatory bioengineered food labeling was less than a penny per day person, or less than $3.65 per year.

Several food industry groups favored the March 25 bill that included the non-G.M.O. labeling provision.

“We have heard loud and clear the message that consumers want to know what’s in their food, and we agree completely that this information should be easily available to them,” said Wade Cowan, a farmer in Texas and president of the American Soybean Association, St. Louis. “At the retail level, though, consumers who want to choose non-G.M.O. foods have to contend with an increasingly confused landscape of different labeling schemes with different requirements. This bill would end confusion for consumers over which food products do not contain biotech ingredients by establishing a national standard for non-G.M.O. labels.”

Connie Tipton, president and c.e.o. of the International Dairy Foods Association, Washington, said, “To enable the free flow of interstate commerce and to more easily provide consumers with the information they are looking for, it is essential that we have a federal system of labeling laws rather than a state-by-state approach.”