I can't tell you the number of times that I've heard "voting for a 3rd party is wasting your vote". I can tell you that that statement is bunk!
My normal, for the simple-minded, retort is: "There will never be a real 3rd party until someone starts voting for them".
In actuality, my 3rd party vote is MORE IMPORTANT to the two main parties than the average voter's vote! This is because, a 3rd party voter is, for the most part, an independent voter. The Republicrats will always have the Republicrats votes and the Demlicans will always have the Demlican vote. EVERY PARTY tries to win the independent vote. So, Republicans cringe when they see Libertarian votes because they are usually lost Republican votes. The Democrats HATE to see Green Party votes because they are.... you know. The Reform Party is full of nut-cases so no one cares about their vote (just kidding).
So, when a 3rd party gets significant votes, the two main parties take notice. This is how 3rd party votes effect national politics.
As for state and local politics, a 3rd party vote is important because it increases the chance of a 3rd party to become a viable national alternative. SO VOTE FOR A 3rd PARTY!
Here's the link: