JACKSON, Miss. — Mississippi is losing billions of dollars in potential economic activity because state leaders, so far, have chosen not to extend Medicaid to hundreds of thousands more people, a nonprofit group said a report Thursday.

Mississippi Health Advocacy Program, which supports wider availability of medical coverage, said Medicaid expansion in the state would generate more than $14 billion in new economic activity, create about 20,000 new jobs and provide a net increase of $848 million in state and local tax collections.