WASHINGTON — Representative Peter DeFazio of Oregon held a press conference Jan. 16 to highlight a letter to President Obama advocating the inclusion of labeling that identifies food products that are bioengineered.

The letter was signed by more than 200 food-safety groups, environmental organizations and food companies with reputations for including natural ingredients, such as Ben & Jerry’s Ice Cream, Stonyfield Farm, Annie’s, Inc. and Amy’s Kitchen.

“While we will continue to support state-level labeling efforts, we believe there should be a mandatory national labeling system,” the letter stated. “F.D.A. has the authority to require food companies to disclose the presence of these novel food ingredients, and the agency has already required labeling of more than 3,000 ingredients, additives and food processes. Moreover, F.D.A. has a duty to act when the absence of labeling would leave consumers confused about the foods they buy. It’s been more than a decade since F.D.A. approved voluntary G.E. labeling, and consumers are more confused than ever. Allowing responsible companies to voluntarily disclose the presence of G.E. ingredients is simply not enough.”

The letter pointed out that President Obama — when campaigning for president in Iowa in 2007 — made a pledge to provide food labeling that includes information about whether ingredients are bioengineered.

“It’s time for the president to fulfill his commitment,” said Food Democracy Now’s Dave Murphy.

“National polls show that 93% of Americans support G.M.O. (genetically modified) labeling,” said Laura Batcha, chief executive officer of the Organic Trade Association. “Consumers increasingly want to know how their food is produced.”

Gary Hirshberg, chairman and co-founder of Stonyfield Farm, said the call to action is not an effort to stop bioengineered ingredients from being introduced, but is simply “an exercise of our rights as citizens to know what we are buying and to be able to choose the ways that our foods are grown.”

Mr. DeFazio and Senator Barbara Boxer of California introduced legislation in 2013 to compel the Food and Drug Administration to implement a mandatory labeling policy to identify any bioengineered ingredients in foods.