[Steve_Seattle]

"Logistically, you have to have a very good reason to cancel a campaign event this late in a swing state. That’s basically giving up on undecideds that may have attended..."

They probably figured that anyone who would show up to see Kaine was already solidly in their camp; he's not the kind of guy who's going to bring in anyone on the basis of his personal charm or charisma.

[TTFlyer]

Just remember this about Kaine:

If Hillary wins Tim Kaine WILL be President some day. And that ought to scare the **** out of everyone.