Most of that cash is spent on television ads, and this year, they are more than ever seizing the wry, comical cultural zeitgeist of the Daily Show and YouTube.
For example, an ad for Democrat Ned Lamont, running for Senate in Connecticut mocks, "Ned Lamont makes a bad cup of coffee. Ned Lamont is a bad karaoke singer..."
"It's a very funny take on negative advertising, isn't it? I think it was great. He was kind of brave too, to karaoke sing. That was very brave of him," Steve Basset says.
And he should know a funny ad when sees one. He's the creative director behind those crazy Geico commercials. Basset's team recruited cavemen to show just how easy it is to use the Geico website.
Humorous adverting in general is fun to watch, but does it work?
"I think humor can work," Basset says. "One danger perhaps, you don't want to be seen though as just a funny guy who doesn't know the issues and doesn't care about them."
Political analyst Evan Tracey says they can be effective. "It's a very good tactic for going negative, without looking so negative, without looking so mean," he says.
But as we get down to the wire, funny is being replaced by just plain mean.
Why? Because they work. A Vanderbilt University study explained that negative ads stick. The brain wiring, the study says, retains negative information more easily than positive information.
"The one true test is that everybody uses negative ads. Not everybody uses funny adds. So obvioulsy, negative adds work or otherwise the politicians wouldn't use them," Tracey says.
So with days to go, the last thing candidates want to do is leave them laughing. That, for now, will have to be left to the Neanderthals guiding you to Geico's website.