(or Why I can’t leave the Republican Party, yet)
It makes sense that political parties choose their own candidates — until it doesn’t.
In American politics, parties usually choose their candidates by primary voting and then each party’s winner competes in the general election. Everyone can vote in the general election, but usually only party members can vote in the primary.* This is plausible, in that fairness suggests that each party should have a chance at self-definition.**
Nevertheless, historically, there have been many times in which belonging to the minority party was tantamount to self-disenfranchisement. If you belonged to Party A, you could certainly vote in the general election, but the winner might be a foregone conclusion if Party A accounted for only a small percentage of the electorate. In such circumstances, the pragmatic strategy would be to join Party B so as to have a say in the primary election (where there might be two relatively strong candidates) rather than wait for an essentially meaningless general election.
In order to avoid this situation, there are times when primaries are open, such as when Party B puts up no candidate at all. In that situation, everyone can vote in the primary.***
Unless someone runs a write-in campaign and thus gets on the ballot for the general election.
That is actually occurring in Duval County in 2016, in two very important races — for State Attorney and for Public Defender. The incumbent State Attorney and incumbent Public Defender have highly publicized problems, mostly self-caused. These problems brought strong, well-qualified Republican opponents into each race.
However, in order to “protect” the incumbents, sham write-in candidates (“dummy candidates”) have entered the races to close the Republican primaries.
So I’ll keep my “R” until after the local primaries — these races are too important (and the choices are too clear) to stand on the sideline. My Trump-exit will have to wait.
*Open primaries, as are held in some circumstances, allow voting without regard to party affiliation.
**Most people would agree that it would be “unfair” for the Tea Party supporters at a University to all join the College Democrats and take over the College Democrats’ platform so as to undermine the “real” Democratic agenda. (It might not seem so unfair for the Tea Party group to try this with the College Republicans.)
***In Florida, we actually have a Constitutional provision to assure this. Florida Constitution, Article VI, Sec. 5(b) [link] (“If all candidates for an office have the same party affiliation and the winner will have no opposition in the general election, all qualified electors, regardless of party affiliation, may vote in the primary elections for that office.“)
****I know some lifelong Democrats who are going to change temporarily, too. It is actually pretty easy, but needs to be done soon.