For decades, the United States government has quietly run the equivalent of its own major museum, amassing about 26,000 works — from New Deal murals to Alexander Calder’s “Flamingo” sculpture — that have been placed in hundreds of federal buildings and lent to hundreds more museums, historical societies and libraries across the country.

But in March, the Trump administration slashed the staff in the General Services Administration who track, maintain and protect that vast and valuable collection from roughly 30 people to fewer than 10, based on interviews with former employees.

Now art experts are concerned that the cuts put this massive portfolio of work, including pieces by some of the United States’ most notable artists, such as Louise Nevelson, Nick Cave and Ellsworth Kelly, at risk.

“Any reduction in staff could severely hinder the care, preservation, and accessibility of these artworks,” said Julie Trébault, the executive director of the Artists at Risk Connection, an organization that seeks to protect artists, cultural workers and artistic freedom.

The concerns are twofold.

The G.S.A. collection is roughly the same size as that of the Whitney Museum of American Art in New York. But where collection management staff at museums typically track, catalog and maintain art held in their main building and a handful of storage spaces, the government collection has been placed in federal offices and private institutions in all 50 states, plus Puerto Rico and the Virgin Islands.