 Regarding elections to the United States Congress, the point of reference is the president's term.There are three classes of United States Senators; each election replaces one class, hence a "midterm election" appears as one-third through the term of one class and two-thirds through the other, while still midway the term of a president.In addition to federal legislative bodies, governors of 36 states and three territories are also up for election during a midterm election.