The senate is run by democrats, the assembly by republicans.
Walker is from wauwatosa. A democrat has about as much chance getting his seat as pat buchannan has of winning elected office in madison.
From what I understand Walker's district may be sliced and diced making it a democratic district, or at least leaving the option open that it would be contested. I believe it is in the hands of the courts. I don't know what the decision will be.(it may have been decided alreaddy)