He could't have won re-election both in Milwaukee County and state-wide multiple times without them.
Well as you said...Reagan Democrats are the key (and the modern day iteration of the same kind of voter of course). Nationally, the way to win them is the way Reagan did - which is to convince them of conservatism, not to convince them you can be a good moderate too! People respond to leadership.
There are 2-3 Republicans running who have shown leadership. Walker is one of those.