France, Oct. 21 -- As the Democrats seek to wrest control of the House of Representatives and the Senate from the Republicans, campaigns are competing for space on television, streaming services and social media.

An $11.6bn total would exceed both the $8.9 billion spent during the 2022 midterms and the $11 billion recorded in the 2024 presidential cycle, according to advertising tracker AdImpact.

"In a highly uncertain election, much more is spent," explains Vincent Michelot, a specialist in US political history and professor emeritus at Sciences Po Lyon.

Competitive races attract more investment, while attack adverts push opponents to respond quickly - sometimes paying a premium for slots already in high demand.

Beyond advertising, c...