Tammy Suzanne Green Baldwin (born February 11, 1962) is an American politician and lawyer who has served as the junior United States senator from Wisconsin since 2013. A member of the Democratic Party, she served three terms in the Wisconsin State Assembly, representing the 78th district, and from 1999 to 2013 represented Wisconsin's 2nd congressional district in the United States House of Representatives. In 2012, Baldwin was elected to the United States Senate, defeating Republican nominee Tommy Thompson. In 2018, Baldwin was reelected, defeating Republican nominee Leah Vukmir. On April 12, 2023, Baldwin announced her candidacy for reelection in the 2024 United States Senate election in Wisconsin.

Baldwin, who is a lesbian, became the first openly LGBT woman elected to the House of Representatives and to the Senate in 1999 and 2013, respectively. She was also the first woman to be elected to either chamber from Wisconsin. Baldwin identifies as a progressive, and she has a consistent progressive voting record. She supports Medicare for All, LGBTQ rights, and gun control, and opposed the Iraq War.