CHEYENNE, Wyo. (AP) - A new federal study concludes that expanding the federal Medicaid system under the Affordable Care Act would help thousands of Wyoming residents suffering from mental illness or substance abuse.

The Wyoming Legislature again this year rejected federal funds to expand Medicaid and offer subsidized health insurance coverage to roughly 20,000 low-income residents.

Governor Matt Mead had pressed for expansion, saying it promised to save the state health department more than $30 million a year by reducing demand on other programs. But many lawmakers opposed to Medicaid expansion say they don't trust federal promises to continue funding.

A federal report released Monday states 6,000 Wyoming uninsured with mental illness or substance use disorders would have qualified for expanded Medicaid under the Affordable Care Act in 2014, the most recent data available.