The agency’s advisers also proposed expanding reviews to scientists’ work on any human, animal or plant pathogen, toxin or agent that could have a serious impact, like modifying a virus in ways that could help it evade immunizations or resistant to drugs.

The recommendations come as Republican lawmakers, now in charge of the House of Representatives, said they aim to probe the NIH’s oversight of research that involves modifying viruses to identify potential threats to humans and develop ways to fight them. The Republicans also want to investigate the agency’s links to an institute in Wuhan, China, that conducts the pathogen research.

Some lawmakers and others assert that the pandemic was caused by a virus escaping from the Wuhan facility. Many scientists and policy makers say the evidence indicates the cause was natural.

The NIH faces the scrutiny while lacking some key leadership, including a permanent director, that could help it navigate the investigations and advocate for the agency in the Capitol, according to supporters who promote the agency in Washington.

Investigations and hearings could presage a fight over the agency’s budget. Some right-wing House Republicans this month extracted a promise from Speaker Kevin McCarthy for spending cuts that could require trimming NIH spending.

The NIH is the federal government’s life-sciences research arm based in Bethesda, Md., funding billions of dollars in scientific studies each year as well as its own explorations.

The agency, which has a $47.5 billion yearly budget, has typically enjoyed support from both Republicans and Democrats, but it has faced criticism from Republican lawmakers more recently.

Some Republicans on key committees last year demanded that NIH officials and leading virologists turn over documents related to the Wuhan lab and the subsequent debate about the origins of the pandemic.

Senate Republicans said last year the Wuhaninstitute was likely the source of the coronavirus that led to the pandemic. Many scientists, however, disputed the report’s findingsand say evidence points to the virus emerging in animals and then spilling over to humans. China has repeatedly denied the virus escaped from one of its labs.

They also criticized Anthony Fauci, who directed the National Institute of Allergy and Infectious Disease during the pandemic before retiring in December, saying he overstated the government’s authority to require precautions and flip-flopped on matters such as how the coronavirus spread and the need for masks.

Dr. Fauci hasn’t been replaced, nor has former NIH Director Francis Collins, who left the post in December 2021 after more than 12 years in the job. Meanwhile, the NIH lost two Republican champions when Sens. Richard Burr (N.C.) and Roy Blunt (Mo.) retired at the beginning of the year.

The House Committee on Oversight and Accountability, headed by Rep. James Comer (R., Ky.), will conduct some of the House Republicans’ probes of the NIH. The lawmakers created a subcommittee on the pandemic to handle the efforts.

The House Energy and Commerce Committee also said it wants to scrutinize the NIH. Republicans on that committee last year sent letters to the agency requesting information about its ties to Wuhan.

The oversight committee plans to investigate the NIH’s oversight of so-called “gain-of-function” research, Mr. Comer said. In those studies, scientists alter a pathogen to explore its potential to infect people and develop ways to fend it off.

“Congress and the American people need to know how taxpayer dollars are being used on gain-of-function research, the decision-making process for approval, and how NIH conducts oversight,” Mr. Comer said.

A Government Accountability Office report released earlier this week found that federal officials needed to step up their oversight of research involving high-risk pathogens that could cause pandemics.

The recommendations released Friday were prepared by two working groups of the National Science Advisory Board for Biosecurity and are set to be discussed and voted on by the board’s full panel next week. The NIH helps administer the panel, which gives advice to the entire federal government.

In their report outlining proposals for bolstering oversight of pathogen research, the NIH advisers said previous policies left room for some risky experiments to be overlooked. It suggested the federal government oversee all studies with dangerous pathogens, including scientists trying to develop vaccines, or research that doesn’t have government funding, for example.

The advisers also said more transparency during reviews of pathogen research would increase public trust. They also recommended that federal officials work with editors of scientific journals and others to find ways to flag parts of studies that may be too risky to publish.

Agency backers said the White House should have moved more swiftly to replace Dr. Collins, who was known as a charismatic advocate for the agency on the Hill, popular on both sides of the aisle.

An editorial in the journal Science last month called the lack of a new pick “a betrayal” of the scientific community.

“We can’t sustain any loss in the NIH budget,” said Ellen Sigal, founder of Friends of Cancer Research, a think tank and advocacy organization. “It would be devastating to the biomedical community and all research.”

The White House said the NIH has strong acting leadership. The NIH said acting Director Lawrence Tabak has represented the agency before Congress many times.

“The search for a permanent director is ongoing and something we take incredibly seriously,” a White House spokesman said.

A new NIH director would need scientific and political chops and to be willing to comply with federal ethics rules and nix any financial ties that could create a conflict of interest, agency advocates said. Many who would be qualified for the post have worked for or consulted for the pharmaceutical industry and may find divesting difficult, the advocates said.

“If they have to essentially, from their perspective, almost take a vow of poverty…that really limits the playing field,” said Stuart Buck, executive director of the Good Science Project, which advocates for NIH reforms.

Write to Liz Essley Whyte at liz.whyte@wsj.com