In a special election on Tuesday, Ohio voters will decide whether to make it more challenging to adopt state constitutional changes, such as a November ballot item that would safeguard abortion rights nationwide.

The Republican-backed constitutional proposal would impose stricter requirements for amendments to be placed on the ballot in the first place and boost the bar for approval of an amendment from 50% to 60% of the vote. Issue 1, which will be on the vote on Tuesday, does not directly address abortion, but the timing is not random. The November referendum that seeks to codify abortion rights in the state constitution would need to be approved by a supermajority of voters if it were to pass.

According to polls, slightly under 60% of voters support the abortion amendment, which suggests that Issue 1 could have a significant impact on the result. Before the referendum, political organisations on both sides of the abortion debate have invested millions of dollars in the state.

More than a year after the United States Supreme Court declared abortion to be illegal nationally, the Republican-controlled legislature planned Tuesday’s election as the latest statewide abortion fight.

In places where pro-abortion Republicans typically dominate the legislature or hold the governor’s office, ballot initiatives have grown to be effective tools for pro-abortion advocates.

Measures that would have stated that the state constitutions of Kansas and Kentucky—both staunchly conservative states—do not protect abortion rights were defeated by voters there and in Kentucky last year.