[2] Starting in the 1880s, Ohio's Mark Hanna was a significant power in the back rooms of the national Republican party.

In 1912, Democrat Woodrow Wilson won with 40.96 percent of the vote, the Republican ticket was split, with Theodore Roosevelt leaving to start the Bull-Moose Party.

[3] The national political upheaval that ushered in the New Deal era in the 1930s benefited the Ohio Democratic Party.

Starting in the 1960s Ohio Democrats began to win more elections with rulings from the United States Supreme Court that required district representation be based on population and not land sized.

By 1990, the Republicans had won a majority on the Ohio Apportionment Board, which draws district lines for federal and state legislative seats.

The 1992 adoption of term limits by referendum further strengthened the party's hand and 1992 marked the last victory by a Democrat (John Glenn) in a statewide race until 2006.

Redistricting after the 2000 census combined with Ohio's term limits laws had Republican officeholders at the federal and state levels struggling with each other to draw federal congressional districts to create safe seats, with the interests of incumbent US representatives clashing with the interests of state legislators facing term limits looking to Congress for their next jobs.

These days, state lawmakers constantly are scouting their next jobs.... [V]isions of Congress dance in their heads.

Meanwhile, congressional incumbents constantly angle for districts they can't possibly lose.Although term limits were pushed by conservative Republican activists in the 1980s, they forced the retirement of Republican Speaker Jo Ann Davidson (R-Columbus) from the House of Representatives in 2001 as well as the leader of the conservative wing of the party, Deputy Speaker William G. Batchelder (R-Medina).

In 2001, Republicans sought United States House of Representatives seats held by Democrats Sherrod Brown and Ted Strickland.

By 2004, Republicans held all six statewide executive offices (governor/lieutenant governor, attorney general, secretary of state, auditor, and treasurer), a two-thirds majority in the state senate and house, a 5–2 majority on the Supreme Court, both seats in the US Senate, and 12 of Ohio's 18 seats in the US House of Representatives.

Between the election of Robert Cupp in 2007, the death of Chief Justice Thomas Moyer, and the appointment of Democrat Eric Brown in 2010, Republicans had controlled all seven seats on the Ohio Supreme Court previously.

In 2008, Democratic presidential candidate Barack Obama defeated Republican John McCain in Ohio.

John Kasich's law that limits public worker's union bargain abilities was voted down by the people of Ohio.

In 2017, Donald Trump helped to install Jane Timken as head of the Ohio Republican Party.

[6][7] The Cincinnati Enquirer wrote that the endorsement was "a rare move that underscores the former president's grip on state GOP officials.

[citation needed] This scandal had a negative effect on the Ohio Republican Party, who lost many seats in Congress after 2006 and the Governorship went to Ted Strickland.