COLUMBIA, Mo. -- A proposal to make it harder to amend the Missouri Constitution passed the Republican-led House on Thursday.

The measure, approved 111-46, would increase the threshold to enact constitutional amendments from 51% of the vote to a two-thirds majority.

Republicans pitched the change after voters approved several constitutional changes in recent years they oppose, including expanding the Medicaid health care program and a since-overturned revamp of how state legislative districts are carved out.

Republican sponsor Rep. Mike Henderson of Bonne Terre said a simple majority is too low a bar to make changes to the Missouri Constitution. He said there's been an increase in amendments in recent years and too many issues that should have been handled as laws have instead been enshrined in the Constitution.

"Our Constitution's a pretty sacred document," Henderson said.

Democrats argued voters have repeatedly turned to the initiative petition process because the Republican-led Legislature has resisted making laws on issues popular with voters, such as medical marijuana and Medicaid.

"We are making it much, much harder for the people of Missouri to do what they've been forced to do year after year after year, when we refuse to do it in here, and take things to the ballot to pass proposals that they know are good for this state," said St. Louis Rep. Peter Merideth, a Democrat.

If approved by lawmakers, the proposed constitutional amendment on constitutional amendments would go before voters for final consideration.

The legislation also would increase the number of signatures required to put initiatives on the ballot.

Now it takes 8% of voters from six out of eight congressional districts to put a measure on the statewide ballot.

Under the current system, petition backers often ignore the most rural districts and focus on collecting signatures where the population is denser. That sometimes means petition gatherers spend a lot of time in urban areas but rarely visit rural areas.

Republicans want to change the threshold to 10% of registered voters from each congressional district. Henderson said that would ensure voters from every region of the state have a say in whether a proposal goes on the statewide ballot.