SIOUX FALLS, S.D. (AP) — South Dakota voters are weighing whether to expand Medicaid health insurance to tens of thousands of low-income residents through a constitutional amendment after the state Legislature resisted expansion for years. If Constitutional Amendment D is approved by a majority vote, it would remove South Dakota from a list of 12 states that have not expanded eligibility for the government health insurance program. People earning up to 138% of the federal poverty level would become eligible for Medicaid. The Republican-controlled Legislature has resisted Medicaid expansion under the 2010 federal Affordable Care Act. But a wide coalition of health care groups backed a well-funded ballot campaign this year.