Ohio voters on Tuesday overwhelmingly approved a ballot measure that will reform the state's redistricting process, creating a mandate for bipartisanship in the decennial remapping process.

With about half the votes counted a few hours after polls closed, about three-quarters of Ohio voters backed the initiative, State Issue One.

The ballot measure asked voters whether they wanted to amend the state constitution to require bipartisan support when drawing new congressional district lines. Any new maps would require three-fifths support in the state House and Senate, including support from at least half the members of the minority party.

If Republicans and Democrats in the legislature cannot agree on a map, a seven-member bipartisan commission would be assigned to draw new maps. Those maps would have to be approved with at least two votes from the minority party.

If the bipartisan commission fails, the legislature would be allowed to try to draw 10-year maps that earn support from one-third of the minority party or a four-year map with only majority support.

The ballot measure was a product of weeks of negotiations between the Republican-led legislature and a coalition of outside groups led by the state League of Women Voters. That coalition gathered more than 200,000 signatures to qualify for November's ballot.

The coalition and legislators eventually agreed on a compromise that won overwhelming, bipartisan support in the legislature, putting it on the May ballot.

The constitutional amendment would also require at least 65 counties to be drawn wholly into a congressional district. New maps could not divide the cities of Cleveland or Cincinnati between districts.

Democrats and good government groups hailed the measure, which puts Ohio in line with states like Iowa, Arizona, Washington and California, also states that draw lines in a bipartisan or nonpartisan fashion.

" Tonight , Ohio voters sent a clear message to politicians and special interest groups across the country who continue to use gerrymandering to rig voting maps by choosing their voters to maximize partisan political advantage," said Karen Hobert Flynn, president of Common Cause.

Even Republicans were on board. State Sen. Matt Huffman (R), who negotiated the deal with fellow Sen. Vernon Sykes (D), told The Hill earlier this year that the reform measure would end the practice of stretching districts across huge parts of the state.

Ohio’s congressional district maps favor Republicans. The GOP holds 12 of the state’s 16 congressional seats, even though the party won only 58 percent of the two-party vote for Congress in the 2016 elections.

Ohio is just one front in the partisan war over how states draw congressional and legislative district lines. Voters in Michigan, Missouri and South Dakota are all likely to face redistricting reform initiatives in November, while the Supreme Court considers redistricting cases involving North Carolina and Wisconsin.