The Constitution prescribes that the Senate be composed of two senators from each State (therefore, the Senate currently has 100 Members) and that a senator must be at least thirty years of age, have been a citizen of the United States for nine years, and, when elected, be a resident of the State from which he or she is chosen. A senator's term of office is six years and approximately one-third of the total membership of the Senate is elected every two years.