The US midterm campaign is set to be the most expensive on record, with total cost projected to reach nearly $12bn (£9bn), according to OpenSecrets, an independent organization that tracks campaign finance.

The latest Federal Election Commission (FEC) filings, which run to mid-October, show more than $9.5bn spent in this cycle. AdImpact reported that the Texas Senate race became the most expensive non-presidential race on record, with more than $573 million spent as of October 30.