Many people look down on third parties for not having any effect, and tell third-party voters not to "waste your vote."
U.S. history shows third parties have had, and continue to have, significant effects on the political system, even when they don't win elections.
Not that minor parties had an auspicious beginning. According to Richard Brookhiser:
The first presidential candidate of a third party in American history was William Wirt, a former United States Attorney General and biographer of Patrick Henry, who received the nomination of the Anti-Masonic Party for the election of 1832. A diffident man, Wirt informed his supporters that he saw nothing wrong with Masonry, and that if his views disturbed them, he would willingly step aside. But the Anti-Masons ignored the demurral, and Wirt and his running-mate, Amos Elimaker, swept the state of Vermont.
Minor parties focusing on single issues often have succeeded in their goal, even when they do not win elections. Abolition of slavery, homesteading, income taxes and Prohibition were all issues raised by minor parties.
Third parties have had success, however. The Republican Party was a minor party when it won the Presidency in 1860.
November 1993, from Bob Waldrop:
In the article "Presidential Power" by political scientist Theodore Lowi, published in Political Science Quarterly, Volume 100, Number 2, Summer 1985 (transcribed without permission), the author considers several popular myths about the two party system and minor parties in America. Myths 4 and 5, on the "Wasted Vote" issue, seemed particularly interesting:
Myth 4: A vote for a third-party candidate is a wasted vote.
Myth 5: A vote for a third party candidate is a mischievous vote, more powerful than a vote for one of the major party candidates, because it helps elect the worst of the two major candidates.
These two myths are taken together because they give contradictory arguments against supporting a third party and thereby prove that myths need not be consistent to be effective.
Take number 5 first. It operates on the very questionable assumption that one of the major candidates is clearly better than the other. But what are voters to do if they have concluded that both major candidates are worse? Recognizing that absurdity, many voters become nonvoters. Since non-voting is stigmatized, nonvoters are usually quiet, thus depriving their nonvote of the influence it should have. Nonvoting, when done loudly, is an important form of participation. But by the same logic, so is a vote for a candidate for a third party, which is the short answer to myth 4. A vote for a third party candidate is never wasted. If the vote is for a dissident party, it is a protest vote that can instill considerable anxiety in the leadership of the major parties. If the vote is for a programmatic third party, a more substantive message is sent; and history shows that these messages are almost always received by the leaders of the major parties.
There is still another type of third party, and a vote for it would be the most effective of all -- if a party of that sort were made available. This is an electorally based third party; a third party just like the two major parties, just as pragmatic, just as concerned with winning elections. Creating such a party on a national scale has not been tried seriously since the Progressives tried it in 1912. The very presence of such a third party would make a fundamental difference to the political system.