Final answer:
The federal opposition parties and leaders in the U.S. include the major party not in control of the presidency or Congress, and various minor parties like the Socialist Party. Leadership structures in the legislature have both governing and partisan roles, helping parties represent the nation.
Step-by-step explanation:
The question asks about federal opposition parties and their leaders. In the United States, the major opposition party has historically been the party that is not in control of the Presidency or Congress. Beyond the two major parties, there are various third parties known as minor parties. Some examples of minor parties include the Socialist Party, which continues to exist in different forms. However, the specific identity of opposition parties and leaders may change depending on the time period in question. For example, in the past, there has been the Anti-Masonic Party, which played a significant role in the 1832 presidential election. It's essential to note that in the U.S., there are separate governing and party structures in the legislature. Leadership organizations within the House of Representatives and the Senate have both government and partisan responsibilities. These structures help the political parties in government to represent not just their parties but also the country as a whole.