I just listed 5 Senate seats that they will almost undoubtedly lose when the current occupant either retires or is defeated. That's a big hurdle that will make it almost impossible for them to capture the Senate in the near future, given the fact that they are expected to lose more seats in the '08 and '10 elections and they are already in the minority.
Landrieu's, Lincoln's, Nelson's, and Pryor's seats are as likely or more likely to fall than Specter's is when they retire.
And you don't see the trend turning around because you're looking at this very narrowly. The 2004 elections saw Democrats losing Senate seats in GA, NC, LA, SC, and FL. So, really it's all going to balance out in the long run. If you're going to look at regional polarisation, look at it in a balanced way. The Democrat's gains in the Northeast are coming on the heels of a forty year shedding of votes in the South.
