In this year's battle for the Senate, both Democratic and Republican candidates in key races have been quite well-funded. But Jacob Fenton of the Sunlight Foundation finds one key difference in where the outside money for each side comes from — spending in support of GOP candidates is much more likely to come from "dark money" groups that don't disclose their donors. Indeed, the GOP advantage in this type of spending has become enormous:
Again, when it comes to outside spending and total spending, the difference between the parties is nowhere near as vast. It's this particular category of dark money spending that the GOP dominates in. Head over to the Sunlight Foundation's site to read Fenton's full breakdown of outside spending in the 2014 midterms.