Ohio has an open primary. The voter registration form does not ask voters to choose a party. On primary day, any voter is free to choose any party’s primary ballot.
In the March 2012 primary, 7,035 Ohio voters chose a Libertarian primary ballot, even though that ballot had no one listed for president, and no one listed for U.S. Senate. President and U.S. Senate are the only two statewide partisan races up in Ohio this year.
Recently, the Ohio Libertarian Party went to the trouble of checking to see which primary ballot those voters had chosen in 2010. The results: 2,797 of the 2012 Libertarian primary voters had not voted in the 2010 primary. 2,987 of the 2012 Libertarian primary voters had also chosen the Libertarian primary ballot in 2010. Also, among the remaining 2012 Libertarian primary voters, 391 had chosen the Republican primary ballot in 2010; 388 had chosen the Democratic primary ballot in 2010; 37 had chosen the Constitution Party primary ballot in 2010; five had chosen the Green Party primary ballot in 2010; 3 had chosen the Socialist Party primary ballot in 2010; and 427 had chosen the non-partisan primary ballot in 2010.