http://conservativetimes.org/?p=5703

Briefly, the role of third parties in our current system is not to win but to punish unfaithful members of the major party closest to your view. But you can’t cast a protest vote for a third party candidate to punish a major party candidate if the third parties don’t exist. So someone has to do the thankless job of maintaining the third party, recruiting candidates, getting them on the ballot, etc. One could believe that reforming one of the major parties and working “within the system” is the long term strategy more likely to be effective and still understand the utility of third parties. By denouncing third parties outright you are taking away one of the potential vehicles for promoting reform from within.

Also, it is not a “wasted vote” if it is cast thoughtfully and strategically to bring about a desired end, such as punishing one of the major party nominees for their deviations.