Credibility has nothing to do with it - check the demographics for the state.
Lowest college graduate rate out of 48 states
Heavy union labor force
Strong Democratic Party
Agricultural (pork barrel Farm Bill)
Etc.
Put up another Democrat with name-recognition then. Same result. Kucinich?
Check these demographics: GOP gov; 2 GOP senators; about a 2/3 majority of House from Ohio is GOP.
I'm not sure, but I think both the state house and state senate are GOP. Bush carried Ohio easily in 00.
Ohio is not a dem state.