COLUMBIA, Mo. -- Missouri's Republican-led House is on track to block funding for a voter-approved expansion of the state's Medicaid health care program after shooting down Democrats' attempts to pay for it Tuesday.

Voters last year amended the state Constitution to offer government health care to thousands more low-income adults, a change that will take effect in July.

But Republican lawmakers, who have long cited concerns about paying for the growing and expensive program, are trying to block the policy's rollout.

The GOP-led House Budget Committee last week voted down a bill to pay to expand health care.

Democrats on Tuesday unsuccessfully tried to add that money back into the budget.

"Missourians were willing to support this legislation when they thought it would cost us money," said Rep. Betsy Fogle, a Springfield Democrat, adding: "If you vote against this, you're sending a clear message that you have no problem with a direct attack on democracy."

Although almost all of Medicaid expansion would be covered by federal funds, some state revenue is required.

The failed bill that would have paid for Medicaid expansion included nearly $1.6 billion, with about $119 million coming from state funds and most of the remaining provided by the federal government.

Republican lawmakers Tuesday argued it's not guaranteed the federal government will continue shouldering most of the costs for Medicaid expansion and cautioned committing to the program could stress the state's budget in the future.

Several said Medicaid should be reserved for the elderly and people with mental and physical disabilities, and opening the program up to other low-income adults will mean less money to care for those vulnerable groups.

Washington Republican Rep. John Simmons said voters "don't want their money going to people that should be able-bodied and are able-bodied."

The state'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 House could send the budget proposal to the Senate as early as this week. Lawmakers face a May deadline to send a spending plan to Gov. Mike Parson.