I wish it truly were “our” primary.
Unfortunately, due to crossover votes in states that don't have voter registration laws, and due to the likelihood of President Obama not having a left-wing opponent in his own party's primary, we're going to see large numbers of independents and moderate Democrats choosing to vote in the Republican Party's primaries.
I understand the problems of having a caucus system in states which, unlike Iowa, do not have a strong tradition of locally-oriented grassroots political activism. However, mandating political party registration that is publicly registered on the voting rolls and must be selected prior to the ordinary cutoff for voter registration (typically a month or so in advance in many states) seems like a reasonable solution.
The alternative is stuff like what happened in our last local election in our county for prosecuting attorney, where the sole Democratic candidate, a well-known local attorney who served many years ago as the county prosecutor, publicly announced that he was going to pick a Republican Party ballot and vote for the weakest of the Republican candidates and encouraged others to do the same on the grounds that it would make it easier for him to win the general election in the fall.
Under Missouri law, that Democrat did nothing illegal or unethical; in fact, he probably did the right thing by publicly disclosing that he had picked a Republican ballot, since he didn't have to tell that to anyone. Requiring political party registration reduces that problem, and creates a publicly checkable track record to see if candidates or their financial supporters have a history of switching political party affiliations when convenient.
I wasn't meaning to imply that we had states which don't require people to register to vote (although same-day registration at the polling places comes dangerously close to that). The problem is that some states don't require people to declare a political party affiliation before being allowed to vote in the primary elections.
Republicans should be deciding who the Republican Party candidate will be. Same for Democrats, or members of the Libertarian Party, Constitution Party, or anyone else. Letting undecided people and independents vote is bad enough; what's even worse is that in too many local elections, one party may have few or no contested races so the members of that party cross over and vote in the other party's primary, doing so not to select the best candidate but rather the candidate they perceived to be the weakest.
Unless someone successfully talks one of the left-wing Democrats into running in the Democratic Party's presidential race on the grounds that President Obama is not liberal enough, we run the serious risk of a lot of Democrats becoming temporary Republicans merely so they can vote for the Republican they believe to be the weakest.