Conservative dark money groups have poured more than $55 million so far into U.S. House and Senate elections this cycle, according to an analysis by Dark Money Watch and MapLight.
Liberal dark money organizations have spent over $19 million, the analysis found.
Most of the $80 million in spending reported by more than 90 dark money groups across the political spectrum has gone to races that could determine which party controls the Senate.
But the reported spending likely doesn’t include all of the expenditures made by those organizations. Dark money groups — politically active nonprofits and limited liability corporations — do not have to publicly disclose their donors and do not have report all of their political spending to the Federal Election Commission. By law, these organizations can spend unlimited amounts of money on ads, mailers, and other materials advocating for or opposing a candidate or issue — as long as the expenditures are made independently of campaigns.
The vast majority of dark money spending in this election cycle has come from a handful of politically active nonprofits. The top three biggest spenders so far — the U.S. Chamber of Commerce; Americans for Prosperity, a conservative dark money organization supported by billionaire brothers Charles and David Koch; and the National Rifle Association — account for more than half of all reported dark money spending on House and Senate elections.
Below are the ten Congressional races where dark money groups are spending the most this cycle, according to the analysis.
- Pennsylvania Senate – $14.9 million
The too-close-to-call contest between incumbent Republican Pat Toomey and his Democratic challenger, Katie McGinty, is now the most expensive Senate race in U.S. history, according to CNBC. It’s also one of six battles that could determine whether the GOP maintains its majority in the Senate.
The dark money groups boosting McGinty’s campaign include Majority Forward, which has spent $2.5 million on ads critical of Toomey, the Environmental Defense Action Fund and the League of Conservation Voters, which have spent more than $2.4 million combined.
- Ohio Senate – $11.3 million
Liberal and conservative dark money groups have been moving some of their resources elsewhere, now that Republican incumbent Rob Portman has a sizable lead in polls over his Democratic rival, Ted Strickland. But when the race was considered close, the organizations pumped millions into the Buckeye state.
Working America, Stand up for Ohio, the SEIU, the Ohio Environmental Council Action Fund and the League of Conservation Voters put in a combined $1.3 million to aid Strickland’s bid.
- Florida Senate – $9.9 million
While polls show a tight race between the Republican incumbent, Sen. Marco Rubio, and Democratic Rep. Patrick Murphy, the dark money spending has overwhelmingly favored Rubio.
American Future Fund has spent $2.6 million on ads critical of Murphy. The organization also spent millions attacking Rubio’s primary opponents during his unsuccessful presidential bid. Americans for Prosperity has spent $2.1 million supporting Rubio, the NRA has spent $1.7 million, and the Chamber has spent $1.5 million.
Much of this spending has gone to ads criticizing Murphy or advocating for Rubio. One ad paid for by the Chamber highlighted news reports questioning Murphy’s resume.
The dark money groups supporting Murphy — AFT Solidarity, America’s Voice, People for the American Way and Working America — have spent about $915,000.
- Nevada Senate – $8.9 million
With Sen. Minority Leader Harry Reid retiring, dark money groups have spent millions on the battle to replace him. Polls show that the race between Democrat Catherine Cortez Masto and Republican Joe Heck is a dead heat.
The Chamber has spent $3.6 million and the NRA almost $1.5 million to support Heck. Americans for Prosperity has reported spending $270,706 and has put resources into a ground campaign advocating for Heck.
Cortez Masto’s bid has received support from three dark money organizations: Majority Forward, which is affiliated with the Senate Majority PAC and has spent more than $251,000; the League of Conservation Voters, which has spent nearly $980,000; and the Environmental Defense Action Fund, which has spent more than $400,000.
- Indiana Senate – $5.7 million
Most of the dark money in this race is aimed at defeating Democrat Evan Bayh, who is running for a seat he last held in 2011, when he retired from the Senate.
Although Bayh became an adviser to the Chamber when he left office, his former employer (as of June) has spent more than $2.5 million aimed at helping his rival, Republican Rep. Todd Young. The Chamber’s political director told the Indianapolis Star the group decided to oppose Bayh because “his voting record is reflexively liberal when it matters most.”
In addition to the Chamber, the NRA has spent $1.9 million and Americans for Prosperity has spent almost $1 million to stop Bayh from reclaiming his Senate seat.
- North Carolina Senate – $4.7 million
Dark money has been streaming into the Tar Heel state in the final weeks of the election, with most of it aimed at helping the incumbent Republican Richard Burr, who, polls show, has a slim lead over former Democrat Deborah Ross.
Since Sept. 27, the NRA has pumped over $1.9 million into the race, spending big on television advertisements and mailers to oppose Ross. Americans for Prosperity and One Nation, a dark money group linked to GOP strategist Karl Rove, together have spent nearly $1.3 million against Ross.
Ross, meanwhile, has benefited from a significant investment by labor. The AFL-CIO has reported spending over $900,000 against Burr.
- Missouri Senate – $4.0 million
As the race between Republican Sen. Roy Blunt and Secretary of State Jason Kander has tightened, dark money has poured in from liberal and conservative groups.
Blunt’s re-election bid has received support from Americans for Prosperity, which has spent $725,000; the NRA and One Nation, which have each spent about $480,000; and the American Chemistry Council, which lobbies on behalf of chemical companies and has spent nearly $292,000. Most of that money has gone to ads and mailers attacking Kander.
The American Federation of State, County and Municipal Employees has spent over $1 million, and Majority Forward has spent about $829,000 on ads attacking Blunt.
- New Hampshire Senate – $3.3 million
Republican Kelly Ayotte’s support of Donald Trump could determine the outcome of this hotly contested race. The incumbent Ayotte, who called Trump a “role model,” before saying she had made “a mistake,” is running against Democratic Gov. Maggie Hassan.
The dark money groups boosting Ayotte’s re-election bid include the Chamber, which has spent $1.9 million, and One Nation, which has spent over $700,000. Citizens for Responsible Energy Solutions, a conservative group that has received funding from nonprofit groups traditionally associated with Democrats, has spent over $450,000. The organization released an ad this summer calling Ayotte a leader who will “protect the legacy of this environment.”
Hassan’s campaign has received outside support from gun safety and reproductive rights advocates. The National Abortion Rights Action League has spent more than $103,000, and Everytown for Gun Safety, a group backed by Michael Bloomberg, has spent about $27,500.
- Nevada Congressional District 3 – $2.0 million
The Republican primary race for the congressional seat being vacated by Heck saw a torrent of dark money spending in support of state Sen. Michael Roberson’s failed bid.
A group called Ending Spending poured more than $1.6 million into the race, running ads backing Roberson and bashing his opponents, including the eventual primary winner, Danny Tarkanian. Ending Spending doesn’t disclose its donors, but it is associated with Joe Ricketts, the conservative billionaire who founded AmeriTrade.
Main Street Advocacy, a group that supports moderate Republicans, chipped in $250,000 to boost Roberson’s bid.
Dark money does not appear to be a factor in the general election, where Tarkanian is running against Democrat Jacky Rosen.
- Wisconsin Senate – $1.9 million
Republican Ron Johnson upset Democrat Russ Feingold in 2010, part of the Tea Party wave that swept through Congress. Now Feingold is trying to recapture his Senate seat, and polls show him in the lead.
Feingold’s bid has received support from the Environmental Defense Action Fund, which has spent more than $468,000; J Street, a liberal Jewish advocacy group, which has spent $125,000; and Everytown for Gun Safety, the Bloomberg-backed gun control group, which has spent $20,000.
Methodology: MapLight analysis of data on electioneering communications, independent expenditures by organizations, and communication costs in 2016 election cycle available from the Federal Election Commission as of October 19, 2016. Organizations’ ideological views are from the Center for Responsive Politics. Expenditures opposing one of two candidates in a race is assumed to support the opposing candidate.