Where are the most expensive midterm races and who is funding them?

US voters head to the polls on Tuesday for the 2026 midterm elections, which are expected to serve as a referendum on Republican President Donald Trump’s performance halfway through his second term. Control of Congress may hinge on a handful of closely contested Senate and House races, with candidates, parties and outside groups spending hundreds of millions of dollars. AdImpact estimated that advertising and reservations totalled $11.21bn as of October 26, compared with $3.2bn during the 2024 presidential election season. Senate contests in Texas, Ohio and Michigan are among the costliest; in Texas, Democrat James Talarico is seeking a statewide win, something a Democrat has not achieved since 1994.