WASHINGTON — Most federal insurance cooperatives created under the Affordable Care Act are losing money and could have difficulty repaying millions of dollars in federal loans, an internal government audit has found, prompting the Obama administration to step up supervision of the carriers.

Daniel R. Levinson, the inspector general at the Department of Health and Human Services, said that most of the insurance co-ops enrolled fewer people than they had predicted, and that 22 of the 23 co-ops lost money last year.

Even as overall enrollments for insurance have increased, many of the co-ops are still losing money, a review of 2015 data by federal health officials shows.

In February, the Iowa insurance commissioner moved to shut down a nonprofit co-op insurer, CoOportunity Health, created with $145 million in federal loans, and a state court found it insolvent because of “adverse claims experience.” Another carrier, the Louisiana Health Cooperative, started with $65 million in federal loans, said it would voluntarily halt operations at the end of this year.