Backers of an open primary constitutional amendment say this ballot measure question is different from a similar ballot question last year.
The constitutional amendment will place all candidates in a primary election on the same ballot. The top two candidates who receive the most votes then move on to the general election in the fall.
Joe Kirby is chair of Open Primaries South Dakota, a group backing the measure. That group also backed Amendment V, a similar measure last year. Kirby says that measure almost passed with 45 percent of the vote.