It may. On the left, I have people telling me that a vote for a third party (instead of Obama) will put Romney in the white house. For myself, I'm willing to take that short term risk. This argument applies to both sides: if the party knows you will always hold your nose and vote for the establishment candidate, they will never actually do what you want, because they know they don't have to. You may stamp and nash your teeth all you like, but if you always fall back into line in the end, you've done nothing.