Robert Califf testifies during the Senate Health, Education, Labor and Pensions Committee hearing on the nomination to be commissioner of the Food and Drug Administration on Tuesday, Dec. 14, 2021.Robert Califf testifies during the Senate Health, Education, Labor and Pensions Committee hearing on the nomination to be commissioner of the Food and Drug Administration on Tuesday, Dec. 14, 2021.

The FDA's response to a nationwide baby formula shortage that has left parents scrambling to feed their children was questioned by U.S. lawmakers on Thursday.

The shortage was caused by the lack of action by the FDA and by corporate greed and consolidation, according to Rep. DeLauro.

Califf is the first administration official to testify before Congress on the shortage, which has sown fear and frustration among parents across the U.S. and prompted lawmakers from both parties to demand answers.

Lawmakers pointed to the closing of an Abbott Nutrition plant in Michigan as a reason for the infant formula shortage. The FDA was criticized for failing to investigate a complaint that accused the company of numerous safety violations at the facility, including failing to properly test baby formula before releasing it.

The FDA closed the plant after four infants who drank formula there contracted infections and two of them died.

98% of the baby formula American parents buy is produced in the U.S. Four manufacturers dominate the market. The supply chain is disrupted when one plant goes offline.

The FDA only began inspecting the Abbott facility several months after the first case of bacterial infection was reported, which was condemned by the chair of the subcommittee.

We need to get to the bottom of the FDA's slow response, which resulted in product staying on the shelf and in the homes of families the country over, potentially putting babies at risk and forcing parents to play a game of Russian Roulette that they did not know they would be.

Califf acknowledged the frustration of parents due to the shortage. The infant formula supply chain has been impacted by a number of issues, including the Covid pandemic, the Russian invasion of Ukraine, and labor supply issues.

The FDA has been working hard to address this issue this week.

One day after President Joe Biden invoked the Defense Production Act to boost the supply of baby formula, a hearing will be held. The president launched a program to import formula from foreign manufacturers.

Hours after the House passed two bills to combat the shortage, a hearing is being held. The main piece of legislation would give the FDA emergency funding to inspect foreign plants for formula and prevent future shortages.

CNBC's Spencer Kimball contributed to the article.