Also referred to as a congressman or congresswoman, each representative is elected to a two-year term serving the people of a specific congressional district. Among other duties, representatives introduce bills and resolutions, offer amendments and serve on committees. The number of representatives with full voting rights is 435, a number set by Public Law 62-5 on August 8, 1911, and in effect since 1913. The number of representatives per state is proportionate to population.
Article 1, Section 2 of the Constitution provides for both the minimum and maximum sizes for the House of Representatives. Currently, there are five delegates representing the District of Columbia, the Virgin Islands, Guam, American Samoa, and the Commonwealth of the Northern Mariana Islands. A resident commissioner represents Puerto Rico. The delegates and resident commissioner possess the same powers as other members of the House, except that they may not vote when the House is meeting as the House of Representatives.
To be elected, a representative must be at least 25 years old, a United States citizen for at least seven years and an inhabitant of the state he or she represents. Source: What is a Representative? U.S. House of Reprresentatives.
The framers of the Constitution created the United States Senate to protect the rights of individual states and safeguard minority opinion in a system of government designed to give greater power to the national government. They modeled the Senate on governors' councils of the colonial era and on the state senates that had evolved since independence. The framers intended the Senate to be an independent body of responsible citizens who would share power with the president and the House of Representatives. James Madison, paraphrasing Edmund Randolph, explained in his notes that the Senate's role was "first to protect the people against their rulers [and] secondly to protect the people against the transient impressions into which they themselves might be led."
To balance power between the large and small states, the Constitution's framers agreed that states would be represented equally in the Senate and in proportion to their populations in the House. Further preserving the authority of individual states, they provided that state legislatures would elect senators. To guarantee senators' independence from short-term political pressures, the framers designed a six-year Senate term, three times as long as that of popularly elected members of the House of Representatives. Madison reasoned that longer terms would provide stability. "If it not be a firm body," he concluded, "the other branch being more numerous, and coming immediately from the people, will overwhelm it." Responding to fears that a six-year Senate term would produce an unreachable aristocracy in the Senate, the framers specified that one-third of the members' terms would expire every two years, leaving two-thirds of the members in office. This combined the principles of continuity and rotation in office.
In the early weeks of the Constitutional Convention, the participants had tentatively decided to give the Senate sole power to make treaties and to appoint federal judges and ambassadors. As the convention drew to a close, however, they moved to divide these powers between the Senate and the president, following Senate Origins and Development Gouverneur Morris' reasoning that "As the president was to nominate, there would be responsibility, and as the Senate was to concur, there would be security." Due to the concern of individual states that other states might combine against them, by a simple majority vote, for commercial or economic gain, approval of a treaty would require a two-thirds vote. In dealing with nominations, the framers believed that senators -- as statewide officials -- would be uniquely qualified to identify suitable candidates for federal judicial posts and would confirm them along with cabinet secretaries and other key federal officials, by a simple majority vote. Source: Senate Origins and Development, The U.S. Senate.