The food safety law puts the burden on food companies to make sure that their products are safe, instead of relying largely on inspectors from the understaffed F.D.A. It requires better record-keeping, contingency plans for handling outbreaks and measures to prevent the spread of contaminants. It also gives the agency the power to issue recalls, something it could not do previously.

Consumer groups have accused the Obama administration of being slow to move the rules through the regulatory process. They sued in 2012 to force the F.D.A. to accelerate its timetable on issuing final rules. A settlement was reached last year, and the agency will publish some of the final regulations this year.

Mr. Taylor, the F.D.A. official, said that the agency had been able to issue new rules, including those for produce and processed foods, but that funding shortfalls would make it difficult to modernize its inspection processes and retrain about 2,000 inspectors and other staff members for the new requirements.

He also said that the agency would have problems providing guidance and technical assistance to the states, which conduct inspections under contract with the F.D.A. In addition, he said, it will be difficult for the agency to properly oversee food imports.

“If they don’t have the capacity to enforce it, the law is not going to be worth the paper it’s written on,” said Tony Corbo, a lobbyist for Food & Water Watch, a consumer group.

At a hearing on the F.D.A.’s budget last month, Representative Harold Rogers, Republican of Kentucky and chairman of the House Appropriations Committee, said that he was concerned about the size of the agency’s overall budget request and that the request for more than $100 million for the food safety law “will be tough to swallow.”

According to the Centers for Disease Control and Prevention, about 128,000 people are hospitalized each year with food-related illnesses, and 3,000 die. The cost of treatment and lost income is $15 billion a year or more, according to data from the Agriculture Department.