Final answer:
Third parties struggle to gain support in the U.S. due to the diverse ideologies among dissatisfied voters, the dominant two-party system's focus on moderate voters, and the structural challenges like the Electoral College and media coverage favoring established parties.
Step-by-step explanation:
Third parties have trouble garnering much support from dissatisfied voters because the ideologies of the dissatisfied voters are so diverse. Discontent amongst voters often spans a wide range of issues, making it difficult for a single third party to represent all their views effectively. In addition, the two-party system in the United States has historically perpetuated itself due to a variety of factors, including but not limited to, the Electoral College system, the relative prosperity of the country's regions not being dominated by mobilized ethnic minorities, and the tendency of the two major parties to aim for moderate voter blocs. Thus, third parties struggle to compete with the resource-rich Democrats and Republicans who have a stronger establishment and media presence, as well as ideological polarization that makes compromise more challenging and often leaves third parties labeled as nonviable options by voters.
It is worth mentioning that critical elections and political realignments can shift voters' loyalties and influence the dominant two-party system but have not yet resulted in a sustainable presence for third-party movements. The lack of success for third parties is compounded by the tendency in individualistic state cultures for electoral competition to focus on party loyalty rather than the personal attributes or the specific agendas of third-party candidates, reducing the tolerance for alternatives outside the traditional two-party contenders.