WASHINGTON — Nonprofit co-ops, the health care law’s public-spirited alternative to mega-insurers, are awash in red ink and many have fallen short of sign-up goals, a government audit has found.

Under President Barack Obama’s overhaul, taxpayers provided $2.4 billion in loans to get the co-ops going, but only one out of 23 — the one in Maine — made money last year, said the report out Thursday. Another one, the Iowa/Nebraska co-op, was shut down by regulators over financial concerns.

The audit by the Health and Human Services inspector general’s office also found that 13 of the 23 lagged far behind their 2014 enrollment projections.

The probe raised concerns about whether federal loans will be repaid, and recommended closer supervision by the administration as well as clear standards for recalling loans if a co-op is no longer viable. Just last week, the Louisiana Health Cooperative announced it would cease offering coverage next year, saying it’s “not growing enough to maintain a healthy future.” About 16,000 people are covered by that co-op.

“The low enrollments and net losses might limit the ability of some co-ops to repay startup and solvency loans, and to remain viable and sustainable,” said the audit report. A copy was provided to The Associated Press.