It sure seems this way sometimes — the GOP and Conservative movements on the Right seem more interested in ideological purity than being a big tent. (The Left can be that way sometimes, too, to be sure, but tend toward being more inclusive.)
The result is more discipline / ideological lockstep in Congress, but some odd conflicts and foot-shooting on fringe candidates. On the other hand, when it comes to the national election, the GOP seem to keep it together for voting purposes, which is a strength (or perhaps weakness) of the Two Party system.
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