1--The popularity of Fox News. The Dems have never experienced fair and balanced before, and without the networks doing their bidding in spinning, the task is harder. Some arguments evaporate in the light of truth and don't stand up to the slightest logical challenge.
2--W. Bush is NOT is father. He's a banty rooster and not a pushover or "let's rise above this" gentleman. He called them on their act and nipped their criticisms in the bud.
It also doesn't hurt to have the history of Clinton's failures in the past as well as the facts of the Democrats' pre-Sept 11 security briefings. They must have realized that they are culpable for their own failures to connect the dots as well as liable if any of their rantings result in security leaks and compromise.
No mas! No mas!
They got hit with a TKO. First Condi Rice, then Cheney, then Laura and George Bush pounded them. Democrats have no one of the stature of any of them and then know it. They were afraid of what was next (thank you Dick Cheney). As you say, they relied on the media and found out fast that was not going to work.