Congress is the highest legislative body in the United States and is held every two years. Congress consists of the Senate and the House of Representatives. Two senators from each state, *** 100, are elected by the voters of each state by universal suffrage for a term of six years, and one-third of them are re-elected every two years. Senators must be at least 30 years old and live in the state they represent. The House of Representatives has 435 members, and each state has at least one representative according to the proportion of population. According to the census results, the number of representatives in each state is redistributed every 10 year. Members are directly elected by voters in their constituencies for a term of two years. After the term expires, all members can be re-elected. Representatives must be at least 25 years old and live in the state where their constituency is located. Members of both houses can be re-elected indefinitely. Members of the Senate and the House of Representatives are full-time, and may not hold government posts concurrently.

The speaker of the Senate is also the vice president, presiding over the Senate meeting and signing the registered bill; Vote only if the Senate has an equal number of votes. The temporary speaker of the Senate is usually the oldest member of the Senate majority party. The Speaker of the House of Representatives is elected from among the members of the House of Representatives. Almost all members of Congress are Democrats or Republicans, and few independents or the third party, party member, often belong to these two parties.

The main functions of Congress are: legislative power, administrative supervision power, constitutional amendment power, and the right to re-elect the president and vice president. Congress can pass resolutions that don't need the president's signature, but these resolutions have no legal effect, and usually only show Congress's attitude towards certain issues. Congress has the power to impeach the president, vice president and other federal government officials. The House of Representatives can impeach government officials by a simple majority vote, and the Senate is responsible for interrogating impeached officials, but their conviction must be supported by two-thirds of the members. The president's appointment of all important government officials must be approved by the Senate.