I really don't want to see the dems take either house, but it's really going to come down to whether or not each individual looks at their candiate and wants to support them wholly (or partially). It's really a difficult decesion, especially in our 'trying times'.
I'm not sure what will happen.
The November election will be driven by Ahmadinejad, as he purposely forces the US to act within an election year. Thus, the immigration issue will pale in comparison to the attempts at dragging us into Armagedden.