But this is simply wrong.
"All politics is local." The national issues that define "the party" may be meaningless or active hindrances locally, which is where candidates are nominated and run. In a strongly "blue" area, you may not be able to find ANY electable candidate that will support all ten -- or even eight of the ten -- planks on that particular purity test. Even if that's the case, you'd be better off finding an electable candidate who supports six of them than insisting that the Republicans must run a candidate who can't help but lose to a zero of ten McGovern Democrat. If you do that, you end up with support for NONE of your ideas in congress, instead of only some of them.
This is the classic mistake of letting the achievable good become the enemy of the unachievable best.