Senate races featuring the biggest independent expenditures totals

Nine of the 10 races that have attracted the most outside spending feature open-seat races. Only the Maine features an incumbent, although South Carolina just became an open-seat election when Sen. Lindsey Graham died on July 11.

Primary elections will be held in Michigan on Aug. 4 and Minnesota on Aug. 11. Democrats in Maine will hold a special convention on July 25 to select a nominee to replace Graham Platner. South Carolina Republicans will hold a special primary on Aug. 11 to replace Lindsey Graham.
Source: OpenSecrets analysis of FEC reports, as of the morning of July 21, 2026Get the dataCreated with Datawrapper