Final answer:
The common nickname for minor political parties in the United States is "Third Parties." They can influence elections by highlighting key issues and splitting the vote, but they generally face significant obstacles within the political system.
Step-by-step explanation:
The common nickname for minor parties that are not part of the two major political parties in the United States is "Third Parties". These third parties sometimes bring important issues to the attention of the major parties and can act as spoilers in elections by splitting the vote. Examples of third parties in the U.S. include the Libertarian Party, the Green Party, the Reform Party, and the Constitution Party.
Third parties can influence U.S. elections by highlighting topics that resonate with the public and sometimes affecting the outcomes of elections due to vote splitting. Despite their efforts, third parties generally face significant challenges in the political system dominated by the Democratic and Republican parties, making it difficult for them to sustain long-term success.
The level of party organization most responsible for helping a party's presidential nominee win the presidency is the national level.