Senators, who serve six-year terms, are elected by popular vote, similar to members of the House of Representatives. The Elections Clause in Article 1, Section 4 of the US Constitution establishes that each state can create its own rules for when, where, and how Senate elections are held, but Congress has the authority to change most of those rules.
When the Constitution was ratified, state legislatures had the power to elect US senators to their six-year terms, not the voting public. This tended to keep Senators loyal to the state powers that sent them to Washington, while also shielding them from sudden changes in opinion. And unlike in the House, no wave elections can overtake the Senate. Only about one-third of the upper chamber is up for election every two years.
But rising political conflict within state governments, along with widespread concerns about corruption, fueled efforts in the late 19th and early 20th centuries to change how US senators were elected. The Seventeenth Amendment, ratified in 1913, changed that system by allowing voters to directly elect their senators.
The amendment also explained that states must hold elections to fill vacant Senate seats, but state legislatures can allow the governor to appoint a temporary senator until such an election takes place. Notably, the Seventeenth Amendment did not change the election or term of any senator who was already in office when it took effect.
In 1892, Rep. Omer Kem of Nebraska spoke in support of the change, saying, “It is quite possible for those who have their million to bribe one, five, ten or twenty votes even in order to accomplish their ends, but it is not possible to bribe a whole State, hence the wisdom of adopting the popular vote in electing all legislative officers.”
