If 2006 goes VERY badly, there might as well not BE a 2008. Do you realize what the 'ruling' party from both houses could do to election laws, funding, etc. in just two short years. It wouldn't even matter that GW is president. There are many actions that could be taken over which he has NO control......
If the Dems take over in 2006, they'll waste the next two years impeaching Bush, and get nothing else done.
Frankly that doesn't scare me as much as you might believe. Nor does it seem very realistic.