[ultima ratio]

You know the media is at war with itself on this. On the one hand it is pulling for Kerry. On the other hand, it smells a BIG story. If Kerry looks any weaker in the polls, the media will move in for the kill, figuring he'd lose anyway, might as well get a good story out of it. Besides, if Kerry goes down with the media defending him still, then it would look worse for them in any post-election analysis. But if they take Kerry down themselves, they avoid that judgment.

[GretchenM]

if Kerry goes down with the media defending him still, then it would look worse for them in any post-election analysis.

All your arguments are valid but I think this is the strongest reason they are backing away slowly.