JEFFERSON CITY, Mo. (AP) — Republican lawmakers on Thursday voted to make it harder to change the Missouri Constitution amid a campaign to restore abortion rights through a voter-backed constitutional amendment.

Currently, Missouri constitutional changes are enacted if approved by a majority of votes statewide. State senators voted 22-9 along party lines to also require a majority of votes in five of the state’s eight congressional districts to approve amendments. The Senate measure now heads to the Republican-led House.

Republican state lawmakers have been fighting for years to raise the bar to amend the constitution, without success. But there is increased pressure this year due to the effort to get the abortion-rights amendment on the November ballot.

If approved by the full Legislature, the Senate’s proposal would go before voters this fall. Some Republicans are hoping the higher threshold for approving constitutional amendments will get on the August ballot so that it could be in place by November, when voters might decide on the abortion-rights amendment.

The Missouri proposal to make it harder to amend the state constitution builds on anti-abortion strategies in other states, including last year in Ohio. Last month, the Mississippi House voted to ban residents from placing abortion initiatives on the statewide ballot.

The Missouri Senate proposal passed days after Democrats ended a roughly 20-hour filibuster with a vote to strip language to ban noncitizens from voting in Missouri elections, which they already can’t do.

“Non-citizens can’t vote,” Republican state Sen. Mike Cierpiot said during a floor debate Tuesday.

Senate Democrats have argued that including the ban on noncitizen voting was so-called ballot candy, an attempt to make the proposal more appealing to Republican voters worried about immigrants.

“I just don’t quite understand why, during election years, it always seems like there has to be a group of people that we’re supposed to be fearful of,” Democratic state Sen. Tracy McCreery said during the filibuster.

Republicans, particularly members of the Senate’s Conservative Caucus, have warned that an explicit ban should be added to the constitution in case city leaders try to allow noncitizens to vote and state judges rule that it is legal. Republican Gov. Mike Parson has said he has filled more than 40% of Missouri’s judicial seats.

“We have a foresight and a vision to see the potential of what could happen in the future here in the state of Missouri with the election process: the illegals voting,” state Sen. Rick Brattin, who leads the Conservative Caucus, told reporters Thursday.