Sen. Ron Johnson, R-Wis., is demanding the Trump administration answer how it is going to end “shell games” through which states artificially inflate their contributions to Medicaid in order to get a greater share of federal funding.

Johnson sent letters on Friday to Centers for Medicare & Medicaid Services Administrator Seema Verma and U.S. Comptroller General Gene Dodaro regarding a lack of audits of states’ use of Medicaid funding.