At this time ,voters have the option of crossing party lines and voting for the candidates of their votes of their choice. In presidential election , their votes are not direct. Each stage has a number of "electors" corresponding to its number of senators and reperesentaives in congress. These electors make up the Electoral Colleag, as defened by The U.S. Constitution. Electors, using the popular votes of their states' voters, really elect the President and Vict President.
Primaries and general elections have different rutes and processes. The opportunity to make choices adout public officals is an essential part of the democratic process.