Final answer:
The obstacles to the success of third parties include a lack of funding, limited media coverage, and difficulty in meeting ballot access requirements. The one factor that does not hinder third-party success is strong support from major political parties, which they typically do not receive.
Step-by-step explanation:
The obstacles to third parties in the United States' political system include various factors but do not include strong support from major political parties, which is actually an advantage, not an obstacle. Among the significant challenges faced by third parties are lack of funding, which major party candidates typically have in abundance, allowing them to campaign more effectively. Moreover, third parties often struggle with limited media coverage, as they are sometimes perceived by media outlets as less newsworthy or not viable, which further hinders their visibility to the public. Additionally, they face difficulty in meeting ballot access requirements that are often tailored to benefit established parties, making it harder for third-party candidates to even appear on electoral ballots. In contrast, strong support from established political parties would provide resources, legitimacy, and easier access to the political arena, which can be decisive factors in a campaign's success.