CHICAGO, July 17 (Reuters) – A group of Democratic attorneys general sued Thursday to block the implementation of portions of a U.S. Department of Health and Human Services rule set to go into effect next month that they say could lead to nearly 2 million people losing their health insurance.

The attorneys general of 20 states, including New Jersey, California and Massachusetts, joined with Pennsylvania Governor Josh Shapiro, a Democrat, to file the lawsuit in federal court in Massachusetts. They argue that the department’s actions illegally change the rules governing state and federal health insurance marketplaces created under the Affordable Care Act and therefore will push more healthcare costs onto the states. The final rule creates barriers to enrollment for health insurance sold on