The GOP has the most primary election contests, but DFL voters may have feelings about best choices on the GOP ballot, and can cross-over vote in the primary. While in November each individual's vote in each contest will be for the candidate thought best, it is nice to feel the best in each party is on ballot, since each election there is a mix of winners from the major two parties (with majorities set by overall election results). Given that the other party's candidate could win any race, it makes sense to cross over if your party lacks major primary contests, in order to assure that the best pairings possible will reach November voters.