More than 600,000 have already lost coverage since pandemic protections ended on April 1 and about 15 million people will be dropped over the next year in the "Medicaid unwinding," as states review participants' eligibility.

When the COVID-19 outbreak started, hollowed-out state and local health departments were ill-equipped to step into the breach.

The U.S. Health and Human Service Department waited until a day before ACA payments were due to notify New York and Minnesota by email that more than $1 billion in annual funding was being cut off, according to a complaint filed in federal court.