do you think the midweek change was the fallout on the ammo dump story?
No.
1) I think the undecideds were available to Bush all along if Kerry didn't show some charisma and intelligent solutions. Kerry has done neither, so they're now moving the way Rove expected all along.
2) Bush's appeals to "discerning Democrats" may be subtely affecting the race. It hasn't gotten a lot of media play, but it's very compelling.
3) I believe there is a backlash against the partisan media. We saw it in 1994 and I think it's happening again.
In short, I think the voters are simply rejecting Kerry as a viable alternative. It doesn't have anything to do with one news item or the other. It's a character thing, so to speak.