The national primary election has to occur first. It is NOT going to be Hilary Clinton, the only democrat against 4 or 5 republican candidates. It is a group of democrats candidates against each other until a single one is chosen to represent the Democratic Party in the national presidential election. And the same for the Republican Party. The National presidential election is usually a Republican, a Democrat, and a third-party member running for president.
P.S. There is no guarantee that Hilary would win against another Democrat in the primary. After all she lost to Obama in a primary.
PLEASE don’t make up your mind on who you are voting for a YEAR in advance from the primary election. Things are way too early!