Breaking from its industry rivals, Campbell Soup will become the first major food company to begin disclosing the presence of genetically engineered ingredients like corn, soy and sugar beets in its products in the US.

The company, the maker of brands like Pepperidge Farm, Prego, Plum Organics and V8 in addition to its namesake soups, is taking the unusual step — and possibly risking sales by alienating consumers averse to genetically modified organisms — as big food corporations face increasing pressure to be more open about their use of such ingredients.

Food companies have begun printing labels to comply with a new labeling law in Vermont, which has become a battleground over labeling that other states have been watching closely. Beginning in July, Vermont will require disclosure of genetically engineered ingredients, a measure opposed by most major food companies, which are seeking to supersede any state’s legislation with a voluntary federal solution.

“We’re optimistic that a federal solution can be reached in a reasonable amount of time, but if that’s not the case, we’re preparing to label all our products across the portfolio,” Ms. Morrison said in an interview.

She said about three-quarters of the company’s products contained ingredients derived from corn, canola, soybeans or sugar beets, the four largest genetically engineered crops. The change in labeling is expected to take 12 to 18 months.

Some companies have reformulated a handful of products to replace such ingredients. General Mills now produces non-G.M.O. Cheerios, and others have put labels on some products verifying that they contain no genetically engineered components, like Tropicana juices.

But none have gone as far as Campbell, whose move is reminiscent of that by Whole Foods Markets, which almost three years ago created an uproar when it announced that, as of 2018, it would require all products sold in its stores to have labels disclosing the presence of ingredients from genetically altered crops.

More mainstream grocers like Kroger and Safeway have moved to highlight their selection of organic products, which by law cannot contain any genetically modified ingredients, and have quietly urged big food manufacturers not to oppose demands for G.M.O. labeling.

The number of products verified by the Non-GMO Project, a nonprofit group that certifies foods that are free of ingredients from genetically engineered sources, is now in the tens of thousands.