In case you didn’t know, the United States political system is dominated by two political parties – Democrats and Republicans. Third parties are any other political party that challenges them – like Independent, Green Party, and Libertarian, to name a few.
Due to the two party political system, third parties rarely win elections. However, we have seen successful Independents win, including U.S. Senators Bernie Sanders and Angus King.
If third party candidates are running and, depending on which ideology they lean towards (whether more liberal or conservative), the candidate typically takes votes away from the major party candidate.
For example, in the 2000 Presidential Election when Ralph Nader ran with the Green Party, a more liberal third party, he took crucial votes away from Democratic candidate Al Gore, which may have lost Gore Florida and allow George W. Bush to win.