I have heard a rumor enough times to wonder how much truth there is to it with regards to Paul Hackett's withdrawal in Ohio...that is that some of the pressure (and some of the swiftboat style rumor-mongering) was genereated by the consultants in DC and in Ohio that stood to lose a significant amount of money if Sherrod Brown didn't get the Democratic nomination.
When you consider what 15-25% of the spending in Ohio is likely to be, you start to see how big money plays a role in these decisions - after all, homes in the DC suburbs and in the tony 'burbs of Ohio are expensive, and insider consultants are just plain entitled to all that money, right?
I haven't dealt with Ohio politics in years so I have no idea, but I'd be curious if you DailyKos folks might be able to shine some light on this subject....