Your argument is premised on the idea that the GOPe is on the side of conservatism. Not even that... that they're on the side of anything LESS than omnipotent government. How much more will it take to prove they are not? The "field that exists" is ALL of them -- Dem, Repub alike -- fighting conservatives and mainstream Americans. There IS no distinction in kind between the socialists and "weak" Repubs. "Weak" is a euphemism for "onboard with Dems."
You are proving my point. The field that exists consists of Dems and Republicans. From my perspective, there are a handful of decent conservatives among the Republicans, but we need to elect more and also empower the few that we have. So, I vote in the primary for the most conservative candidate, then vote for the Republican even if it’s the one I didn’t want. It would be great to clean the slate and start with all new people, but that is not the field that exists. My argument is not based on the notion that the GOPe is on side of conservatism, but that even the most liberal Republican is to the right of Harry Reid. And if they only vote my way 1 time out of a l00, that is still better than never at all. That is the field that exists.