The Republican-controlled Missouri Senate voted 23-9 along party lines Wednesday to kill legislation expanding Medicaid eligibility to roughly 300,000 uninsured, lower-income adults.

Despite Gov. Jay Nixon’s (D) vocal support for expanding Medicaid, the state’s Republican-led legislature repeatedly defeated Democrats’ efforts to advance similar proposals last year.

"It's the easiest and simplest way to improve our health care in our state, improve our economy," state Sen. Paul LeVota (D), who spearheaded the amendment, said on Wednesday, according to the St. Louis Post-Dispatch. "This isn't a crazy idea. This is an idea whose time has come."

Approximately half of U.S. states have expanded Medicaid under the Affordable Care Act, which offers participating states federal payments covering the full enrollment costs of newly eligible participants from 2014 to 2016.

Despite the estimated $1.7 billion Missouri would have received from the federal government in 2015, Senate Appropriations Committee Chairman Kurt Schaefer (R) argued that costly Medicaid bills would divert from education funding, according to the Associated Press.

"We cannot afford it," Schaefer said.

Former Republican U.S. Sen. Kit Bond (R-Mo.), a vocal opponent of President Barack Obama’s landmark health law, served as one of the lone conservative voices pushing for Medicaid expansion in his home state.

"While I was and still am one of the loudest opponents of Obamacare, I'm getting involved in Medicaid reform now because if our state sits on the sidelines, I'm concerned hospitals in rural and inner-city Missouri won't survive,” Bond said in a January email.

Missouri's current eligibility cap is about $4,500 annually for a family of four, the lowest threshold permitted under federal law. LeVota's amendment aimed to expand Medicaid eligibility to include Missourians making up to 138 percent of the poverty level, or slightly below $33,000 a year for a family of four.