Two states, Connecticut and Maine, have passed laws requiring the labels, though both require neighboring states to pass similar laws before going into effect.
A bill in Congress, the Genetically Engineered Food Right-to-Know Act, has gained support in both chambers from a bipartisan group of lawmakers.
Lawmakers like Sen. Richard Blumenthal (D-Conn.) have said that state laws should lead the way for federal action.
Supporters of the labels consider them a basic matter of transparency for critical consumers who might have unresolved questions about GMOs.
Agriculture groups, however, contend that GMOs do not pose a threat to human health and are necessary to feed a growing global population.