The feds are letting Indiana, which is now the 10th Republican-run state to expand Medicaid, make several changes to the program that could discourage low-income people from seeking care.
While Arkansas looks to replace its first-of-a-kind model for expanding Medicaid, Gov. Asa Hutchinson urged lawmakers to renew it through 2016.
Most states refused to keep funding a pay raise for Medicaid doctors this year, but the first national study of the policy shows it increased low-income patients' access to primary care.
The case could halt private lawsuits against state Medicaid agencies over doctor pay.