Ohio constitution
Article V: elective franchise
Section 7

All nominations for elective state, district, county
and municipal offices shall be made at direct primary
elections or by petition as provided by law, and provision
shall be made by law for a preferential vote for
United States senator, but direct primaries shall not
be held for the nomination of township officers or for
the officers of municipalities of less than two thousand
population, unless petitioned for by a majority
of the electors of such township or municipality. All
delegates from this state to the national conventions
of political parties shall be chosen by direct vote of
the electors in a manner provided by law. Each candidate
for such delegate shall state his first and second
choices for the presidency, but the name of no candidate
for the presidency shall be so used without his
written authority.