The issues are limited government: Specifically the complete roll back of the Federal system vs Leviathan. Limited foreign intervention vs Endless engagement. Economic liberalism vs Government controlled Corporate Monopoly. Tax reform: specifically limited taxation, localism, and fiscal restraint vs Confiscatory taxation and trillion dollar deficit spending.
If a candidate isn't talking about that then they are worthless. If this country is stupid enough to send another Bush and Clinton to the table, then it probably is beyond fixing "teh stupid".