The candidates have raised an extraordinary amount of money in an election awash with cash on an unprecedented scale

It was one of the most striking images of the final full week of the presidential election campaign: a giant projection of Kamala Harris’s face on the 516ft-wide, 366ft-tall Las Vegas Sphere.

At a reported $450,000 per day for what is believed to be the first political ad to appear on the futuristic new attraction, it was also one of the most expensive. But even at those rates, it barely made a dent in the staggering election war chest of almost $1bn that Harris has built since replacing Joe Biden at the top of the Democratic ticket this summer.