Kyrsten Lea Sinema is an American politician and former social worker serving as the senior United States senator from Arizona, a seat she has held since 2019. A former member of the Democratic Party, Sinema became an independent in December 2022.

The United States Senate is the upper chamber of the United States Congress. The United States Senate and the lower chamber of Congress, the United States House of Representatives, comprise the federal bicameral legislature of the United States. Together, the Senate and the House maintain authority under Article One of the U.S. Constitution to pass or defeat federal legislation. The Senate has exclusive power to confirm U.S. presidential appointments, approve or reject treaties, and try cases of impeachment brought by the House. The Senate and the House provide a check and balance on the powers of the executive and judicial branches of government.