Georgia is an Open Primary State

What does this mean?

Unlike many other states, voters in Georgia do not register by party affiliation. At each General Primary election voters may select either a Democratic, Republican or Nonpartisan ballot. That choice is not limited in any way by the ballots voters have selected in previous elections, nor does it limit their choice in future General elections. Therefore, a voter may choose to select a Democratic ballot in the July Primary election and then choose to select a Republican ballot in the following November General election and vice versa.

Relevant Georgia election codes are: O.C.G.A. Sections 21-2-2 and 21-2-402.