The United States is a multi-party system, with the Democratic Party and the Republican Party being the most powerful. However, other parties, such as the Reform, Libertarian, Socialist, Natural Law, Constitution and Green Parties, can also promote candidates in a presidential election. These parties have occasionally challenged Democrats and Republicans, but since the rise of the Republican Party to the category of major party in the 1850s, minor parties have had only limited electoral success. In 1912, for example, former Republican President Theodore Roosevelt challenged Republican President William Howard Taft, dividing the votes of the Republicans and allowing Democrat Woodrow Wilson to win the presidency with only 42 percent of the vote.
Similarly, in 2000, Green Party candidate Ralph Nader's 2.7 percent of the votes may have tilted the presidency toward Republican George W. Bush by drawing votes that would otherwise have been cast for Democrat Al Gore. The Green Party is a progressive political party that seeks to build a socially and racially just, ecologically sustainable, democratic and peaceful ecosocialist society that exists in harmony with nature. The Libertarian Party, on the other hand, has been at the forefront of defending issues such as marijuana legalization, marriage equality, school choice, gun rights, competition in transportation and an end to mandatory minimum sentences and asset forfeiture laws.
The Peace and Freedom Party is a working-class party that opposes foreign wars and wants to bring troops home from abroad. The California Republican Party works to make California better by providing safety for families, education opportunities, jobs and business opportunities. American political parties have weak central organizations and little central ideology except by consensus. In the early 21st century, political experts routinely divided the United States into red and blue states whose assigned colors not only indicated which political party was dominant at the local level but also indicated the supposed prevalence of a set of social and cultural values.
American electoral politics has been dominated by successive pairs of major political parties since shortly after the founding of the Republic of the United States. Former Secretary of Labor Robert Reich promotes the idea that there are six political parties in America. Third political parties have appeared in US history from time to time but rarely lasted more than a decade. The United States is home to a wide variety of political parties beyond just Democrats and Republicans.
From Green Parties to Libertarians to Peace and Freedom Parties, these minor parties have occasionally challenged major party candidates in presidential elections. While they have had limited success in terms of electoral victories, they still play an important role in American politics by bringing attention to issues that may not be addressed by major parties. They also provide an alternative for voters who may not agree with either major party's platform.