A Quinnipiac poll in February showed nearly the same margins.
The poll also found that women, young people and Democrats all support gay marriage in higher numbers than men, older Ohioans and Republicans.
The survey of 1,174 Ohio voters was conducted by phone from May 7 to 12. It has a margin of error of 3 percentage points.
This material may not be published, broadcast, rewritten, or redistributed.