JEFFERSON CITY, Mo. (AP) — The court trial over Missouri officials’ refusal to expand Medicaid is set to begin Monday.

Three low-income woman sued Gov. Mike Parson’s administration last month after the Republican said he won’t expand Medicaid, even though voters last year amended the state Constitution to do so.

Missouri’s Medicaid program currently does not cover most adults without children, and its income eligibility threshold for parents is one of the lowest in the nation at about one-fifth of the poverty level.

The constitutional amendment kicks in July 1 and applies to an estimated 275,000 more adults.

The plaintiffs argued in the lawsuit that they need the health insurance program to get treatment for illnesses including asthma and diabetes.

The Missouri Attorney General’s Office is defending Parson’s administration in court. Attorneys for the office have argued that because the Republican Legislature didn’t include funding to expand the program in the state budget, Parson cannot implement the expansion.

“The General Assembly has not provided the necessary appropriations authority,” the Attorney General’s Office wrote in response to the lawsuit. “And Defendants’ lack of appropriation authority to expand taxpayer funds means they cannot implement Medicaid Expansion.”