Since Montana became a U.S. state in 1889, it has sent congressional delegations to the United States Senate and the United States House of Representatives. Each state elects two senators to serve for six years. Before the Seventeenth Amendment took effect in 1913, senators were elected by the Montana State Legislature. Members of the House of Representatives are elected to two-year terms, one from Montana's at-large congressional district. Before becoming a state, the Territory of Montana elected a non-voting delegate at-large to Congress from 1864 to 1889.

Raymond Jon Tester is an American politician and farmer serving as the senior United States senator from Montana, a seat he has held since 2007. A member of the Democratic Party, Tester is the dean of Montana's congressional delegation and the only Democrat who holds statewide office in Montana. He served in the Montana Senate from 1999 to 2007, and as its president for his last two years in the chamber. He is generally considered a centrist or moderate Democrat.