The United States's mid-term elections this year will take place on Tuesday. The following are some questions and answers about the elections.

Q: What are the mid-term elections?

U.S. mid-term elections

A: According to the U.S. Consitution, the presidential election is held every four years and the Congressional elections are held every two years. The Congressional elections held between presidential elections are known as mid-term elections, which mostly take place on the first Tuesday in November.

Q: Who are involved in the mid-term elections?

A: Congress is the supreme legislative body of the United States and it consists of the Senate and the House of Representatives. Both senators and representatives are chosen through direct elections by each of the 50 states. Each state, regardless of population, has two senators in the 100-member Senate, who serve six-year terms. Every two years, one-third of the Senate is re-elected.

Members of the 435-seat House are elected by each of the 50 states according to their popuplation and serve a two-year term. The current Congress is the 111th Congress in U.S. history.

According to the U.S. Constitution, any candidate running for a seat in the Senate must be 30 years old or above, and must be a U.S.citizen for seven years or above and a resident in the state where he or she registers for the elections. Any candidate running for a seat in the House must be 25 years old or above, and must be a U.S. citizen for seven years or above and a resident in the state where he or she registers for the elections.

Meanwhile, during the mid-term elections, voters in some states also elect their state governors, most for a four-year term, and some for a two-year term.

Q: What is the importance of the mid-term elections?

A: The mid-term elections, in essence, is a struggle between the Democratic Party and the Republican Party for control of Congress. Currently, there are 59 Democrats (including two Independents) and 41 Republicans in the Senate, and 255 Democrats and 178 Republicans in the House, with two vacancies.

In the upcoming mid-term elections on Tuesday, Democrats and Republicans will vie for all the 435 seats in the House and 37 seats in the Senate as well as the posts of 37 governors.