COLUMBUS, Ohio (AP) — After a critical vote Wednesday, the Ohio House agreed to send to voters in August a measure making it more difficult to amend the state’s constitution, just months before an amendment guaranteeing abortion rights lands on the statewide ballot.

It asks voters to raise the threshold for future constitutional amendments from 50% plus one to a 60% supermajority.

The Ohio Statehouse resounded with protests before the House voted to approve the resolution.

The measure needed to return to the Senate for a technical vote before heading to the Ohio Secretary of State’s office, which has set an 11:59 p.m. deadline.

Its success capped a monthslong effort led by a faction of Republican lawmakers and the state’s GOP elections chief and carried out by anti-abortion and gun rights groups.

Since the U.S. Supreme Court overturned its landmark Roe v. Wade ruling guaranteeing abortion rights last year, other states’ amendments involving the procedure have shown voter support for legal access to abortion is between 50% and 60%, whether in conservative Kansas, Democratic-leaning Michigan or Republican-leaning Kentucky. But no vote has exceeded 60%.

Among maneuvers used to get the resolution past its GOP opposition was to remove language Tuesday that would send the question to an August ballot. Opponents of that strategy bristled at the fact that it was only in January that a new election law was signed eliminating most August special elections.

State Rep. Sharon Ray, who offered the amendment pushing the 60% question to Ohio’s next scheduled general or special election, said an August election would add “another level of complication” to the already tough job of local election workers.

“I made a promise to our board of elections,” the Republican said. “Remember, these are our neighbors and friends that work very hard to provide flawless elections for us — most of them volunteers, they get paid a mere stipend — and, I guess, I appreciate their sacrifice.”

Opponents planned to continue their fight ahead of the scheduled vote. A broad coalition of voting rights, faith, labor, civil rights and community groups planned a massive protest ahead of Wednesday’s vote. It’s the second in a week. Every living ex-governor of the state, and both Republican and Democratic former attorneys general, also oppose the constitutional change, as does the Ohio Libertarian Party.