I'm creating this topic in response to a off-topic discussion that started in another thread. The question raised there was whether the Republican Party in particular is welcoming toward internal dissent.

I'd like to make the discussion broader than that, though. The more general problem, I think, is how any political party manages dissent. Do dissenting voices get drowned out so that only the extremes are represented in party platforms and candidates?

I'd be most interested in actual, personal examples...