Outside spending — expenditures by groups other than candidates themselves — is pouring into the races that will determine control of the U.S. Senate. As part of our series on money in key Senate races, the Brennan Center has examined the outside spending in 10 close contests. New data will become available in the next week that will allow us to paint a full picture of spending trends in 2016’s most competitive Senate races.
In the meantime, our preliminary analysis reveals two important trends: The increasing dominance of just three interests, the Democratic party and affiliated outside groups, the Republican party and affiliated outside groups, and the Charles and David Koch political network; and the shift of resources away from official party committees and toward “shadow party groups,” super PACs and nonprofits controlled by party operatives but legally permitted to take unlimited and often secret donations.