What Does a Senator Do? How Many Senators There Are, How Long They Serve and How They Are Elected

By Dr. AtlasPublished Sep 17, 2026

A U.S. senator has two jobs that the Constitution spells out. The first is shared with the House of Representatives: making federal law. “All legislative Powers herein granted shall be vested in a Congress of the United States, which shall consist of a Senate and House of Representatives.” ^[1] The second belongs to the Senate alone: confirming or rejecting the president's nominees, approving treaties, and trying impeachments. ^[1][3]

There are 100 senators, two from each state, elected by the state's voters to six-year terms. ^[2][4]

What does a senator do?

Senators write, amend and vote on bills. A bill has to pass both chambers before it reaches the president: the Constitution speaks of “Every Bill which shall have passed the House of Representatives and the Senate.” ^[1] One difference is written into the text. “All Bills for raising Revenue shall originate in the House of Representatives; but the Senate may propose or concur with Amendments as on other Bills.” ^[1]

Powers only the Senate has

• Nominations. The president nominates ambassadors, Supreme Court justices and other officers of the United States and appoints them “by and with the Advice and Consent of the Senate”; Congress may by law let the president alone, the courts or department heads appoint “inferior Officers.” ^[3] “The vast majority are routinely confirmed,” the Senate says of nominees, and in its history it “has confirmed 126 Supreme Court nominations and well over 500 Cabinet nominations.” ^[5]
• Treaties. The president can make a treaty “provided two thirds of the Senators present concur.” ^[3] In the Senate's own words, “The Senate does not ratify treaties”; after its Committee on Foreign Relations considers one, it “either approves or rejects a resolution of ratification.” ^[6]
• Impeachment trials. The House “shall have the sole Power of Impeachment,” which it uses by simple majority. ^[1][7] The Senate has “the sole Power to try all Impeachments,” and “no Person shall be convicted without the Concurrence of two thirds of the Members present.” ^[1] Conviction means removal from office; in some cases the Senate has also barred the official from holding office again. ^[7]

How many senators are there?

One hundred. The Senate's party-division table lists 100 total seats, and its page on cloture refers to “the 100-member Senate.” ^[4][11] After the 2024 elections the division was 53 Republicans, 45 Democrats and 2 independents, according to the Senate's party-division table as read on September 17, 2026; the Senate cautions that the numbers often change during a Congress “due to the death or resignation of a senator, or as a consequence of a member changing parties.” ^[4]

How many senators per state?

Two, whatever the state's population. The 17th Amendment reads: “The Senate of the United States shall be composed of two Senators from each State, elected by the people thereof, for six years; and each Senator shall have one vote.” ^[2]

The vice president is “President of the Senate, but shall have no Vote, unless they be equally divided.” ^[1] For the days when the vice president is away, the Senate chooses “a President pro tempore.” ^[1]

How long is a senator's term?

Six years. ^[2] The Constitution divided the first Senate into three classes “so that one third may be chosen every second Year” ^[1], and the rotation has continued since. The Senate's account of the reason: “To further distance the Senate from democratic pressures, the framers of the Constitution also provided that only one-third of the Senate would stand for election every two years.” ^[10]

A term begins on January 3 after the election; the statute says a senator is elected “for the term commencing on the 3d day of January next thereafter.” ^[9] The class on the ballot in 2026 is Class II, whose terms “run from the beginning of the 117th Congress on January 3, 2021, to the end of the 119th Congress on January 3, 2027.” ^[8]

How are senators elected?

By the voters of the whole state. The original Constitution had senators “chosen by the Legislature” of each state. ^[1] The Senate's history says that “electoral deadlocks in state legislatures along with growing public concern about corruption in Senate elections led to calls for reform.” ^[10] The 17th Amendment replaced the legislatures with the people: “The states ratified the Seventeenth Amendment in 1913, and the first popular Senate elections were held in 1914.” ^[2][10]

Anyone qualified to vote in elections to the larger chamber of the state legislature may vote in a Senate election; the amendment's wording is “the qualifications requisite for electors of the most numerous branch of the State legislatures.” ^[2] The Ledger explains the general rules in who can vote in U.S. elections.

Federal law places the contest on the November ballot: a senator is chosen “At the regular election” held before the term expires, the same one “at which election a Representative to Congress is regularly by law to be chosen.” ^[9] Everything else is mostly state law, because the Constitution leaves “The Times, Places and Manner of holding Elections for Senators and Representatives” to each state's legislature. ^[1]

To serve, a person must be at least 30 years old, “nine Years a Citizen of the United States,” and an inhabitant of the state he or she is chosen to represent. ^[1] The Senate, like the House, is “the Judge of the Elections, Returns and Qualifications of its own Members.” ^[1]

What happens when a Senate seat becomes vacant?

The 17th Amendment requires an election: the state's governor “shall issue writs of election to fill such vacancies.” ^[2] A legislature may also let the governor make a temporary appointment “until the people fill the vacancies by election as the legislature may direct.” ^[2]

What is the filibuster?

The Senate defines it as “a loosely defined term for action designed to prolong debate and delay or prevent a vote on a bill, resolution, amendment, or other debatable question.” ^[11] The way to end one is called cloture. In 1917 the Senate adopted a rule allowing a two-thirds majority to end debate, and “In 1975 the Senate reduced the number of votes required for cloture from two-thirds of senators voting to three-fifths of all senators duly chosen and sworn, or 60 of the 100-member Senate.” ^[11]

That 60-vote threshold now applies to legislation, not to nominations. “Today, filibusters remain a part of Senate practice, although only on legislation. The Senate adopted new precedents in the 2010s to allow a simple majority to end debate on nominations.” ^[12]

The filibuster grew out of what the Senate calls its “tradition of unlimited debate”; the Constitution says only that “Each House may determine the Rules of its Proceedings.” ^[1][11] Opinion on it has long been split, and the Senate's own history page gives both views in one line: the right of unlimited debate is “praised as the protector of political minorities from the tyranny of the majority, or attacked as a tool of partisan obstruction.” ^[12]

The same page lists the longest individual speech: Cory Booker of New Jersey “spoke for 25 hours, 5 minutes, against the policies of the Donald J. Trump administration in April, 2025.” It also records that Strom Thurmond of South Carolina “filibustered for 24 hours and 18 minutes against the Civil Rights Act of 1957.” ^[12]

Which Senate seats are on the ballot in 2026?

The 33 seats of Class II are up on Tuesday, November 3, 2026. ^[8] Special elections to finish unexpired terms in other classes can share that ballot; the Senate's party-division table notes that Ohio's Class 3 seat fell vacant in January 2025. ^[4] The Ledger's 2026 Senate map lists every seat on the ballot, and its race pages follow the contests in Texas, Georgia, North Carolina, Michigan, Maine, Iowa, Nebraska, New Hampshire and Ohio.

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