Article 1, Section 3 of the Constitution creates the United States Senate. It gives each state two senators, sets six-year terms staggered so only about a third of seats turn over every two years, lists the qualifications a person must meet to serve, places the Vice President at the head of the chamber, and hands the Senate the exclusive power to try impeachments. The Seventeenth Amendment later replaced the original method of choosing senators — selection by state legislatures — with direct election by the people.
Two Senators Per State and Six-Year Terms
Every state sends two senators to Washington, regardless of population. Each senator votes independently, so the two senators from one state often land on opposite sides of the same bill. Terms run six years, three times the length of a House term. The longer term was deliberate: the framers wanted one chamber less exposed to short-term shifts in public mood, with room to work on policy that outlasts a single election cycle.
Staggered Elections and the Three Classes
The Constitution divides the Senate into three classes so that roughly one-third of the seats come up for election every two years.1Constitution Annotated. Article I Section 3 At any moment, at least two-thirds of the chamber consists of members already in office. A single election can shift the majority, but it cannot replace the entire body. This rotation has run without a break since the first Senate sorted itself into classes in 1789.
Qualifications to Serve
Three constitutional requirements apply to anyone seeking a Senate seat. A senator must be at least 30 years old, must have been a U.S. citizen for at least nine years, and must be an inhabitant of the state they represent when elected.2Constitution Annotated. Article I Section 3 Clause 3 – Qualifications Each threshold sits higher than the matching rule for the House, where members need to be 25 and to have held citizenship for seven years.3United States Senate. About the Senate and the U.S. Constitution – Qualifications
One additional bar sits outside Article 1. Section 3 of the Fourteenth Amendment disqualifies any person who previously swore an oath to support the Constitution as a federal or state officeholder and then engaged in insurrection or rebellion. Congress can remove that disqualification for a specific individual, but only by a two-thirds vote in both chambers.4Constitution Annotated. Fourteenth Amendment Section 3
How Senators Are Chosen Today
The original text of Article 1, Section 3 had senators “chosen by the Legislature” of each state.1Constitution Annotated. Article I Section 3 State lawmakers picked who would go to Washington, and voters had no direct say. Deadlocked legislatures sometimes left seats vacant for months, and the process invited corruption.
The Seventeenth Amendment, ratified April 8, 1913, rewrote that clause.5National Archives. 17th Amendment to the U.S. Constitution: Direct Election of U.S. Senators Senators are now elected by the people of each state, and anyone eligible to vote for the largest branch of the state legislature is eligible to vote for senator.6Congress.gov. U.S. Constitution – Seventeenth Amendment
Filling a Vacancy
If a senator dies, resigns, or is expelled mid-term, the Seventeenth Amendment tells the governor to issue a writ of election so voters can pick a replacement. State legislatures may also authorize the governor to make a temporary appointment to hold the seat until that election.6Congress.gov. U.S. Constitution – Seventeenth Amendment Most states have granted that appointment power, though rules differ. Some require the appointee to be from the same political party as the departing senator; others impose no such condition.7United States Senate. Appointed Senators (1913-Present)
Who Presides Over the Senate
The Constitution names the Vice President of the United States as President of the Senate.8Constitution Annotated. Article I Section 3 Clause 4 The role is largely ceremonial. The Vice President does not debate, does not introduce legislation, and has no regular vote. The one exception matters: when the Senate splits evenly, the Vice President breaks the tie, and that vote can decide major legislation and confirmations.
Because the Vice President is seldom on the floor day to day, the Senate elects a President pro tempore to preside in the Vice President’s absence.9Congress.gov. Constitution of the United States – Article I By long tradition, the position goes to the most senior member of the majority party, though nothing in the Constitution requires that. The President pro tempore also sits third in the presidential line of succession, behind the Vice President and the Speaker of the House.10USAGov. Order of Presidential Succession
The Sole Power to Try Impeachments
Clause 6 gives the Senate “the sole Power to try all Impeachments.” The House votes to impeach, which works like a formal charge; the Senate alone decides whether to convict. Every senator sitting for a trial must be under oath or affirmation, a reminder that they are acting as jurors rather than as ordinary legislators.11Congress.gov. Article I Section 3 Clause 6
When the person on trial is a sitting president, the Chief Justice of the United States presides in place of the Vice President, who would otherwise stand to inherit the office.11Congress.gov. Article I Section 3 Clause 6 That requirement applies only to a sitting president. When the Senate tried a former president in 2021, the President pro tempore presided, because the Chief Justice’s constitutional obligation no longer applied once the defendant had left office.12Constitution Annotated. ArtI.S3.C6.2 Historical Background on Impeachment Trials
Conviction takes a two-thirds vote of the senators present, one of the highest thresholds anywhere in the Constitution.11Congress.gov. Article I Section 3 Clause 6 Removal is meant to be difficult, reserved for misconduct serious enough to draw a broad bipartisan majority.
What the Senate Can and Cannot Impose
Clause 7 caps the Senate’s punishment at two things: removal from office and, in a separate vote, disqualification from holding any federal office in the future.13Legal Information Institute. Overview of Impeachment Judgments The Senate cannot fine, imprison, or otherwise criminally punish the official. Impeachment is a political remedy for keeping unfit people out of federal office, not a criminal proceeding.
That cap does not protect a convicted official from ordinary prosecution. The Constitution states that the convicted party “shall nevertheless be liable and subject to Indictment, Trial, Judgment and Punishment, according to Law.”13Legal Information Institute. Overview of Impeachment Judgments The Senate decides whether the person keeps the office. The courts decide whether the same conduct broke the law.