What is the role of the senate? Congress? House of Representatives?

That's worth spelling out clearly, because the words "Congress," "Senate" and "House" get used interchangeably in the news, and they aren't the same thing.

It came up here because Dr. Annie Andrews won a seat in the US Senate, and that matters quite differently from winning a House seat.

Congress: the whole building

It consists of two chambers: the Senate and the House of Representatives. Both chambers have to agree on the same text of a bill before it goes to the President to be signed into law. Beyond lawmaking, Congress declares war, approves the federal budget, confirms federal judges and Cabinet officials (Senate), originates revenue bills (House), and has the power to impeach the President.

The Senate: the slower, more deliberate chamber

The Senate has 100 members, 2 from each state, serving 6-year terms. Every state gets equal weight here, Wyoming the same as California. That was a deliberate design choice: the framers intended the Senate to be an independent body of responsible citizens who would share power with the President and the House of Representatives. To guarantee senators' independence from short-term political pressures, the framers designed a six-year term, three times as long as that of popularly elected members of the House.

The Senate has powers the House doesn't. Treaties negotiated by the President need Senate approval, and the threshold is high: two-thirds of senators present must vote yes. The Senate also confirms presidential appointments, meaning Cabinet secretaries, federal judges and Supreme Court justices all go through a Senate vote. And when the House impeaches someone, the Senate adjudicates the impeachment proceedings, acting as the trial jury.

This is what Andrews won. South Carolina now has 2 senators, and she is one of them.

The House of Representatives: the faster, louder chamber

The House of Representatives, with its large membership and two-year terms, was built to reflect the will of the people and respond quickly to public concerns. Representatives are elected based on a state's population, with the total number capped at 435. A large state like California has 52 seats; a small state may have just 1.

The House has 2 exclusive powers. The Origination Clause in Article I, Section 7 requires that every bill raising revenue begin in the House, so all tax legislation starts there. And the House alone can impeach the President, Vice President, federal judges, and other federal officers, with the Senate then deciding guilt.

Why the two-chamber design?

To balance power between large and small states, the Constitution's framers agreed that states would be represented equally in the Senate and in proportion to their populations in the House. The House moves faster and is closer to voters. The Senate moves slowly on purpose, which is why the news about Andrews winning a Senate seat carries more long-term weight than a House race would. Senate seats are rarer, the terms are longer, and the individual power of a senator is considerably greater.