Future of some state-run health insurance markets threatened by low enrollment, high overhead

State-run health insurance markets that offer coverage under President Barack Obama's health law are struggling with high costs and disappointing enrollment.

That means more could turn over costly operations to the federal government or join forces with other states.

Hawaii is the latest to delegate sign-ups to the federal HealthCare.gov. Nevada and Oregon did so last year.

Twelve states and the District of Columbia are running their own markets. Experts estimate that half face financial problems. Federal taxpayers invested nearly $5 billion in state startup grants, and most has been spent.

Now that the Supreme Court has ruled the Obama administration can keep subsidizing premiums in all 50 states through HealthCare.gov, there's no downside to states turning over costly operations, such as sign-up websites and call centers, to Washington.