I have believed this for quite some time now, but all this talk about a sweeping victory by the Dems this November is a little premature. First of all a lot of the Democratic candidates are running against incumbents. Taking a look at how voters traditionally express themselves, they have to be very unhappy with who's in office. Voters have to be unhappy on election day not one, three, or six months earlier. They also have to be unhappy about basic issues, and be convinced that the alternative is indeed a better solution.
The Democrats also need to dump their strategy of playing off the nation's unease of the Iraq quagmire by calling for an immediate withdrawl of troops. It's an attempt at reminding voters of the withdrawl from Vietnam 30 years ago. But that was a different time, different situation, and a different war. Bush ultimately owns the authority to call for the withdrawl of troops from Iraqi soil. If he calls for an immediate removal of troops at current levels right before election time, then this strategy bombshell can easily cause a quagmire for the DNC.
To quote Barry Casselman, the author of the article I read, "These days, we seem to want the future to be clear and present now. The trend of the moment is mistaken for an outcome ahead. History does not seem to work that way. History bobs and weaves in defiance of our logic. History always loves to surprise us."