When I first started voting in Minnesota, some 30 years ago, Minnesota had a non-partisan system for state offices. All candidates were listed together on the ballot, with no party designation. Parties were just as strong, perhaps stronger than they are now. They held conventions to determine which candidates they would endorse, but you had to rely on newspaper reports or the party's advertising to know which party endorsed which candidate--the ballot didn't tell you. For each office, the two candidates who got the most votes in a primary would appear on the ballot in the general election, regardless of whether they belonged to the same party, different parties, or no party. In other words, the primary served as a way of narrowing the field from many candidates to just two. I thought it was a good system. Independents had a better chance of being elected in those days. But then they went and changed the system to a more conventional one. It's rare now for an independent or third-party candidate to get elected, Jesse Ventura notwithstanding.

In Minnesota, at least you don't have to register as a member of a party. At primaries, you are given a ballot that lists each party in a separate column. You are instructed to vote in only one column. If you vote in more than one column, your whole ballot is invalid and won't be counted. I THINK if you misunderstand the instructions, and spoil your ballot, your ballot will be immediately rejected by the voting machine, and you will be given a chance to change it--but I have never seen this happen. In any case, no one knows which party's primary you voted in.

Yes, it is possible to cast a "sinker" ballot, but I think that practice is foolish and rarely done. It would work like this: suppose I am a loyal supporter of Party-A, but the candidate I like in Party-A is virtually certain to win the primary. I could, theoretically, vote in the Party-B column and deliberately vote for the weakest candidate, the one that I think the Party-A candidate could most easily defeat in the general election. Trouble is, by doing that, I'd give up my chance to cast a primary vote for ANY Party-A candidate in ANY office that happens to be on the ballot at the same time. It seems like a bad tradeoff to me, but others may see it differently. And I think it seems dishonest to most people, although there is nothing to stop you from doing it.

I think the main reason we often have weak or extremist candidates on the ballot is that too few voters take the trouble to either attend party caucuses or vote in primaries. Extremist or one-issue voters are simply more likely to show up. Voter turnout at primaries is very low, but attendance at party caucuses is even lower. It's a shame really.