Congressional Republicans, sharpening their attack lines against Democrats ahead of midterm congressional elections, are working to capitalize on a national baby formula shortage to hammer away at President Biden and his party.

At a news conference on Capitol Hill on Thursday, House Republicans blamed Mr. Biden for the shortage, saying his administration had failed to plan for it and calling it the latest failure by the president to deal with the economic challenges facing voters.

The focus on the baby formula crisis, which has affected a broad swath of Americans and sent desperate parents scouring empty drugstore aisles for food, dovetailed with the message Republicans hope will win them victories in November: that Mr. Biden and Democrats have been feckless on issues like inflation and rising gas prices that matter most to regular Americans.

Representative Elise Stefanik, Republican of New York, said the administration should have had a plan for the shortage months ago, while others faulted the president for simply making family life more difficult across the board.

“My son, Sam, is nine months old, he’s formula-fed,” Ms. Stefanik, the No. 3. House Republican, said, noting that parents are racking up high gas bills as they drive around hunting for formula. “The shelves have been fairly empty.”

Republicans held their news conference hours before the White House was expected to announce more actions the federal government is planning to take to address the crisis, according to a report by CNN.

Though the event was focused on the most basic of human needs, hard-right Republicans transformed it into a forum for airing some of their favorite attacks against Mr. Biden, trying to tie the formula shortage to his border policies and even efforts to reduce drug overdoses.

“Pictures are emerging today from the border, where the Biden administration has been sending pallets of baby formula for illegal mothers and their babies while American mothers and babies cannot find baby formula,” said Representative Marjorie Taylor Greene, Republican of Georgia.

Ms. Greene appeared to be referring to a video posted on Facebook this week by Representative Kat Cammack, Republican of Florida, in which Ms. Cammack claimed that a border agent, whom she did not name, shared photographs of baby formula deliveries to an immigrant processing facility in Texas.

A photograph Ms. Cammack shared on Twitter of a shelf filled with infant formula contained no proof that it was taken at the border facility, as she claimed.

A White House official said that since 1997, it has been compulsory under the law for border personnel to have nutrition, including baby formula, for people and infants taken into custody. The official noted that the same policy was followed by the Trump and the George W. Bush administrations.

Ms. Greene also encouraged expecting mothers to breastfeed their babies.

“You cannot depend on this government that is supposedly running our country to create the right conditions in our country for you to find baby formula,” she said.

Many mothers who work at low-wage jobs have few opportunities to breastfeed, and many mothers struggle to produce enough breast milk to nourish their babies.

Representative Mike Waltz, Republican of Florida and the new father of a four-month-old baby, floated a hypothetical that he was heard work-shopping with colleagues ahead of the news conference.

“Think about the fact that in Joe Biden’s America, it seems like it’s easier to get a crack pipe in a government-funded smoking kit than it is to find baby formula,” he said. He was apparently referring to a debunked claim, stoked by a conservative news website, that the Biden administration planned to pay for crack pipes as part of a drug overdose prevention program.

Some veteran House Republicans sought to keep the focus on the baby formula shortage, denying that they were trying to make a political statement.

“This is not meant to be a partisan exercise,” said Representative Patrick McHenry, Republican of North Carolina. “But we’ve come together because we don’t see Democrats raising the same issue, or willing to work with us to get some answer from this administration. So we’re demanding answers.”

House Democrats announced this week that they would hold two hearings on the issue in the next two weeks.