WASHINGTON, United States -- The White House vowed Thursday to take action to boost supplies of baby formula as President Joe Biden was slammed by Republicans for crippling shortages nationwide.

Last week the average out-of-stock rate for baby formula was 43 percent, according to Datasembly, which collected information from more than 11,000 retailers.

The administration, already under fire over the highest inflation rate in decades, said it was considering increasing imports, as the United States relies on domestic producers for 98 percent of the infant formula it consumes.

Officials say they are also working with the states to cut red tape on poor families buying infant milk through food stamps.

Biden has asked the Federal Trade Commission to look into abuses linked to the shortage, including the resale of infant milk online at prices far above normal.

The president met manufacturers and retailers for discussions described as "productive and encouraging" by an administration official, who spoke on condition of anonymity.

However, the official would not say how long it would take for the situation to improve.

The Republican opposition, which has set its sights on wresting back control of Congress in November's midterm elections, has seized on the issue to berate Biden and the Democrats.

Elise Stefanik, part of the House Republican leadership and a new mother herself, told a news conference she had contacted the US Food and Drug Administration in February but received "no substantive response."

"Joe Biden simply has no plan. In fact, when Joe Biden's White House was asked about the shortage, they laughed. Shameful," she told reporters.

Her Republican House colleague Anne Wagner of Missouri said her state was one of six where more than half of the normal supply of baby milk was out of stock.

"I've heard stories of moms firsthand -- my own daughter-in-law -- bartering for baby formula on Facebook," she said.

"Pregnant women are asking if they should start stockpiling. They're anxious during a time of high stress and anxiety."

Congressman Randy Feenstra said families in his state of Iowa were traveling up to 100 miles to source the formula.

The American Academy of Pediatrics recommends exclusive breastfeeding for about the first six months of a baby's life, and continuing to offer a mix of breast milk and solid food until their first birthday.

But the ability to breastfeed can depend on factors such as the mother's work environment and medical condition. Infant formula is considered a healthy alternative and in practice three quarters of babies are fed with at least some formula by six months.

The shortages have been worsening since February 17 when, after the death of two infants, manufacturer Abbott announced a "voluntary recall" for formula made at its factory in Michigan -- including Similac, a brand used by millions of American families.

A subsequent investigation cleared the formula, but production has yet to resume, exacerbating already ongoing scarcity caused by supply chain problems and labor shortages.

"I think we need to take a moment and think about the fact that, in Joe Biden's America, it seems like it's easier to get a crack pipe and a government-funded smoking kit than it is to find baby formula," said congressman Mike Waltz of Florida, a father of a four-month-old.