A state can pass legislation outlawing sanctuary cities and requiring local law enforcement to cooperate with federal officials in retaining illegals.
Walker has a GOP legislature. There is no reason for him not to do this if he is serious about illegal immigration being controlled and enforced.
Wisconsin has far more important things to worry about. We are more than a thousand miles from Mexico. ....so his elimination of a sanctuary designation would be a symbolic waste of time..but whatever. My taxes and other regulatory issues matter more here.