Why is Kerry campaigning in the middle of the night, in Ohio?
The real question is why Bush isn't behind in Ohio by 10 percentage points. Some polls actually have Bush ahead, which is remarkable, given the jobs situation there. At this point, you'd have to say that if Bush wins Ohio, he wins the election.
The "midnight madness" bit is exactly like college basketball, of course. Lots of schools do a "midnight madness" practice, on the first day they can hold practice. You'll probably want to be at "The Ralph" on October 15. I hear it's crazy there.
But, for politics: The norm is that you don't do major campaign events during the other side's convention. But the convention ends on Thursday! So, at 12:01 on Friday morning, it is okay to hold an event.
Bush may get a good convention bounce, which Kerry can't afford (Kerry is sinking already!). So, Kerry wants to make the bounce look like a guitar string: plucked, makes noise for a little while, but then settles down to pretty much where it started out.