The Senate has 100 members, two per state. The House has 435, based roughly on states' population as of the most recent census.Senators serve a six-year term; representatives serve a two-year term, making them more responsive to (and responsible for) voter confidence. According to the U.S. Constitution, senators must be at least 30 years old; representatives can serve starting at age 25. Only the House can propose revenue bills; only they can determine whether a government official can be tried for crimes against the United States Only the Senate can confirm treaties, and confirm or reject presidential appointees. Only they can conduct a trial against government officials for crimes against the U.S. (and only after the House authorizes them to do so).The president of the House is known as the Speaker, and is elected by a majority vote of the majority party) at the time. The Speaker of the House is second in line in as the matters of presidential succession.The president of the Senate is the Vice President of the United States, who is by definition first in line in matters of presidential succession. However, the Vice President only votes to break a tie.In day-to-day matters, the head of the Senate is known as the President pro tempore of the Senate; and while it is technically an elected position, it is usually reserved for the most senior (longest-serving) senator of the majority party. The President pro tempore is third in line in matters of presidential succession.