This is exactly, precisely how politics used to work, how politics is actually supposed to work: 

The Republican race is about to become granular. The coming battles will be waged in targeted congressional districts where Trump shows weakness regardless of his statewide appeal, in hand-to-hand competition at state party conventions where the delegates are being selected, and ultimately in a battle for the hearts and minds of the men and women who will go to Cleveland, bound or unbound on the first ballot but free agents after that.