Missouri residents approved a ballot measure expanding Medicaid in a blow to Gov. Mike Parson, a Republican, on Tuesday.

More than 53% of voters supported expanding Medicaid, compared with roughly 46% who voted no, the St. Louis Post-Dispatch reported.

In this July 7, 2020, file photo, Missouri Gov. Mike Parson speaks during an event at the White House, in Washington. (AP Photo/Alex Brandon, File)

"We did it!" pro-Medicaid Expansion group Yes On 2 wrote Wednesday on Twitter. "Missouri just voted #YesOn2 to expand Medicaid, and now, because of YOUR vote, over 230,000 hardworking people will have access to life-saving healthcare!"

Missouri’s Republican-led Legislature has repeatedly rejected Medicaid expansion proposals over the past decade, prompting supporters to turn to the initiative process.

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Idaho, Maine, Nebraska, Oklahoma and Utah have all expanded Medicaid through ballot questions following inaction by state lawmakers, according to the nonpartisan Kaiser Family Foundation.

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.

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The ballot proposal will expand eligibility under the terms of the 2010 federal health care law signed by President Barack Obama. That law provides a higher-than-usual federal funding share for states that expand Medicaid coverage to adults earning up to 138% of the federal poverty level, about $17,600 for an individual or $30,000 for a family of three.

The office of Democratic Auditor Nicole Galloway, who won the Democratic primary for governor on Tuesday, said the financial impact on the state was not clear. The office has estimated that expanding Medicaid could cost the state at least $200 million or save as much as $1 billion annually by 2026. Republican opponents cited the potential costs as reason to oppose the ballot initiative.

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Parson, who opposes Medicaid expansion and won the Republican primary for a full term, moved the vote on the proposal up from the Nov. 3 general election to Tuesday’s primary. Parson said the earlier vote would give the state more time to financially prepare for Medicaid expansion if it was passed. He said his decision was not about politics.

The Associated Press contributed to this report.