New failures are piling up among the member-run health insurance co-ops carrying out one of the Affordable Care Act’s most idealistic goals, leaving just seven remaining when the health law’s fourth enrollment season starts in the fall.

There were 23 in 2014.

For the rest — which all posted annual losses in 2015, according to the National Alliance of State Health Co-Ops — survival is job No. 1. Some are diversifying to serve larger employers, no longer limiting themselves to their ACA mandate to offer health plans to individuals and small businesses. A Maryland co-op has sued the federal government to avoid paying millions of dollars to other insurers under the ACA’s complex formula to keep premiums stable by balancing risks among insurers and helping ailing ones. Other co-ops are trying to renegotiate contracts with hospitals and other providers.

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