Campaign advertising spending in the US has reached unprecedented levels ahead of the midterm elections, with Republicans leading the October spending surge amid growing concerns over losing control of both chambers of Congress.

According to AdImpact, Republican groups spent $1.9 billion on political ads in October, averaging more than $60 million a day. Democrats spent $1.76 billion, while independent groups accounted for another $350 million, taking total monthly expenditure to a record $4.01 billion.

The 2026 election cycle is now the most expensive in US history, with $11.2 billion already committed to advertising and future reservations. AdImpact estimates the final figure could reach $11.6 billion.US midterms: Who is funding the campaign?

Several wealthy donors and political action committees (PACs) are driving the massive spending. On the Republican side, the Senate Leadership Fund has directed more than $460 million towards battleground races. Elon Musk's America PAC has also emerged as a major contributor, raising $216 million and spending $172 million during the reported election cycle. Other significant Republican-backed groups include MAGA Inc., One Nation and No Going Back.'

We're hot now': Trump defends his leadership in final message to voters, touts oil prices and US global standingDemocratic-aligned spending has received substantial support from Majority Forward and organisations linked to billionaire investor George Soros, with both contributing more than $100 million to political campaigns. Where is the money being spent? Texas Senate race tops $500 millionA significant share of the advertising budget is concentrated in competitive Senate contests. The Texas race between Democrat James Talarico and Republican Ken Paxton has attracted more than $500 million in ad spending.

Federal Election Commission filings analysed by Newsweek indicate that Talarico has faced over $200 million in opposition spending, the highest among candidates.

Ohio's Sherrod Brown and Michigan's Abdul El-Sayed follow, with $168.5 million and $127.8 million, respectively. Meanwhile, Maine has emerged as the most expensive state contest on a per-capita basis. According to USA Today, nearly $218 million was spent on broadcast advertising there by October 28, equivalent to approximately $160 per resident.

The upcoming midterm elections will decide which party controls Congress during the final two years of Donald Trump’s second presidential term. Races for governorships and state legislatures will also influence local policies on key issues, including education, reproductive rights, taxation and election administration.

Historically, midterm elections have often proved challenging for the party in power. Since 1946, the president’s party has lost seats in the House of Representatives in 18 of the 20 midterm elections, highlighting the electoral hurdles Republicans face.