The Trump administration is urging states to change a rule that will give psychiatric patients more places to stay while they receive treatment for serious mental illness.

The change would pay for Medicaid patients to get mental health care for up to 30 days in a facility, such as a hospital, even if it has more than 16 psychiatric beds. That’s not allowed under current Medicaid law, through a rule known as the institutions of mental diseases exclusion, or “IMD exclusion.” The rule has been in place for decades, but the Trump administration says it’s time for a change, and many advocates agree.