People typically vote for a third-party candidate because they are trying to send a message to the major parties. That protest vote is often heard. Both the Democrats and Republicans have accepted reforms and programs that originally seemed radical when presented by third parties. The eight-hour workday, women's suffrage, and the railroad rate regulation are good examples.
Can someone who's not a Republican or Democrat win an election?
Historically, third parties eventually fail to maintain themselves at the local and state levels, usually because one of the major parties skims off their talent by embracing some of the issues that party supporters hold dear. The Populists, Progressives, and Socialists succeeded for a time in winning local and state elections, and even some congressional seats, but their numbers were too small to have a dominating influence.
Third parties often lack the financial resources to mount effective campaigns. Today, the cost of running for office is staggering. The two major parties consolidate their dominance of the political system by staging high-profile primaries and national conventions subsidized by taxpayer money. They exclude third-party candidates from most debates, especially those for national office. Although he held around 5 percent support in the polls, for example, Ralph Nader could not participate in the 2000 presidential debates. Indeed, he was not even allowed to sit in the audience, despite possessing a ticket!