Here’s where things get even more interesting: If you take it a step further and combine all spending by conservative and liberal outside groups, a majority of the money spent by these kinds of groups expressly for or against a candidate — 53.8 percent — has been used to attack Republicans ($9.7 million from conservative groups and $13.8 million from liberal groups), while a measly 8.5 percent has been used to attack Democrats.

The GOP is spending 64 percent of all the money used on ads for or against candidates this year, but its candidates are bearing the brunt of more than six times as many attacks ads as Democrats.