Introduction

The days of candidates dominating their own political campaigns are over.

In the most competitive U.S. Senate races this year, big-money special interests that proliferated after the U.S. Supreme Court’s Citizens United v. Federal Election Commission decision are routinely out-muscling and out-messaging the candidates themselves.

This power shift is most prominent on television, where super PACs and politically active nonprofits — both may accept unlimited contributions — routinely account for nearly one out of every two ads run in a U.S. Senate race. Most of the ads are decidedly negative, and they’ve collectively cost hundreds of millions of dollars with Election Day still 10 days away.

Wealthy liberals and conservatives alike are complicit, pumping money into these groups that, by law, may not operate “in concert or cooperation with” the candidates or parties they seek to boost.

This stands in stark contrast to the 2010 midterm election, when the GOP embraced super PACs while Democrats shunned them. Now, big-dollar liberal groups sometimes trump their conservative counterparts as both seek to support candidates who will help their preferred party win control of the U.S. Senate during the final two years of Barack Obama’s presidency.

The Democratic Party is defending more than a half-dozen seats on Republican-friendly turf. The GOP will seize power if it picks up six seats. These stakes have created a financial arms race that will almost certainly make this election historically expensive.

“Everybody wants to have one more nuke than the other guy does,” says Kathy Kiely, managing editor of the nonpartisan Sunlight Foundation, which tracks money in politics.

Senate TV ads in key races by sponsor

Source: Center for Public Integrity analysis of Kantar Media/CMAG estimates of ads aired from Jan. 1, 2013, through Oct. 20, 2014. More here.

Democratic super PACs on top

When it comes to money, two Democratic super PACs reigned supreme through mid-October, according to a Center for Public Integrity review of filings submitted to the Federal Election Commission Thursday.

NextGen Climate Action — a super PAC primarily funded by billionaire environmentalist Tom Steyer that aims to “prevent climate disaster and preserve American prosperity” — has raised more than $76 million since it was launched in 2013. No other super PAC has raised more.

Earning the No. 2 spot was Democratic-aligned Senate Majority PAC, a group run by allies of Senate Majority Leader Harry Reid, D-Nev. It had raised more than $53 million as of Oct. 15, including $5.5 million from Steyer and his NextGen Climate Action super PAC.

The top three Republican super PACs, meanwhile, raised nearly $68 million combined through mid-October, according to recent FEC reports.

That includes $28 million raised by American Crossroads, a super PAC launched after the Citizens United ruling in 2010 with assistance from GOP strategist Karl Rove.

The Freedom Partners Action Fund, the super PAC backed by conservative billionaire industrialists Charles and David Koch and their donor network, raised more than $20 million.

And nearly $19 million was raised by the Ending Spending Action Fund, a group founded by longtime Republican donor Joe Ricketts, the former head of online brokerage firm TD Ameritrade whose family owns the Chicago Cubs baseball team.

Nonprofits — which aren’t required to disclose the same financial details to the FEC and may generally keep their funders’ names secret — have also played a major role during the 2014 battle for the Senate, especially on the conservative side.

Most notably, groups within the Koch brothers’ political network reportedly plan to spend as much as $290 million.

On the television airwaves, though, where voters still consume most of their political information, arms race metaphors are particularly apropos: In the 12 most-competitive U.S. Senate races, liberals and conservatives have nearly fought to a draw.

Total TV ads in the 2014 battle for the Senate through Oct. 20

Source: Center for Public Integrity analysis of Kantar Media/CMAG estimates of ads aired from Jan. 1, 2013, through Oct. 20, 2014. More here.

Republicans and their allies were responsible for 50 percent of the roughly 633,000 Senate-focused TV ads that have so far aired in Alaska, Arkansas, Colorado, Georgia, Iowa, Kansas, Kentucky, Louisiana, Michigan, North Carolina, New Hampshire and South Dakota, according to a Center for Public Integrity review of data provided by Kantar Media/CMAG, an advertising tracking service.

Democrats and their allies were responsible for 48 percent. And independents — namely Greg Orman in Kansas and Larry Pressler in South Dakota — were responsible for the rest.

GOP candidates generally relied more heavily on support from super PACs and nonprofits than Democrats did.

In these 12 U.S. Senate races, about 52 percent of all Republican-aligned TV ads were sponsored by outside groups, according to Kantar Media/CMAG. Only about 37 percent of all Democratic-aligned ads were produced by such groups.

Other ads were aired by candidates, parties or parties working jointly with candidates.

The official arm of the Democratic Party focused on Senate elections — the Democratic Senatorial Campaign Committee — raised nearly $129 million through the end of September, according to federal campaign finance filings.

That was some $30 million more than the $98 million raised by its rival, the National Republican Senatorial Committee.

Even as many candidates also raised millions of dollars, if not tens of millions — as many incumbent senators have done — they have, nevertheless, regularly been out-spent by super PACs and politically active nonprofits that are unfettered by contribution limits.

A definitive tally of precisely how much has been raised and spent in the key U.S. Senate races this election is difficult because not all groups report numbers the same way or at the same time. Further complicating the issue, as of Friday morning, some Senate candidates’ recent contribution reports were still being processed by the government.

Nevertheless, some races stand out.

Take North Carolina, for instance, where incumbent Democratic Sen. Kay Hagan and Republican challenger Thom Tillis have raised a combined $30 million through the end of September.

Non-party, outside groups there have already reported spending about $50 million on political ads to the FEC — and millions more have been spent on issue ads that need not be reported to the nation’s top elections regulator.

Similarly in Colorado, incumbent Sen. Mark Udall, a Democrat, and Republican challenger Cory Gardner, have raised $29 million through mid-October. Super PACs and nonprofits have so far spent more than $40 million.

Senate candidate fundraising through Sept. 30

Source: Center for Public Integrity analysis of campaign finance filings covering money raised through Sept. 30, 2014, for entire election cycle. Figures for races in Georgia, Kansas, New Hampshire and North Carolina come in part from media reports.

The new normal

Political observers agree that the outsized role of outside groups like super PACs and politically active nonprofits has become the new normal for hotly contested elections.

“Barring any changes to the current regulations, it’s likely that outside group involvement in competitive contests is here to stay,” says political science professor Erika Franklin Fowler, director of the Wesleyan Media Project, which monitors political advertising.

No U.S. Senate election has seen more ads from groups that are neither candidate committees nor parties than North Carolina.

Of the 90,000-plus Senate-focused TV ads that have aired in the Tar Heel State, these so-called outside groups have aired more than 51,000 TV ads, according to a Center for Public Integrity review of data provided by Kantar Media/CMAG. That’s nearly three of every five.

Meanwhile, super PACs and politically active nonprofits account for more than half of all ads aired in the U.S. Senate races in both Michigan and Arkansas.

That ratio is more than 40 percent in the U.S. Senate races in Colorado, Alaska and Kentucky.

And in New Hampshire, where Democratic incumbent Sen. Jeanne Shaheen is facing a stiff challenge from former GOP Sen. Scott Brown — and a multimillion-dollar assault from conservative groups supported by the billionaire Koch brothers and Republican strategist Rove — outside groups account for more than one of every three ads, according to Kantar Media/CMAG.

In all these races, super PACs and nonprofits are also combining to spend tens of millions of dollars on other kinds of communications, from radio spots and glossy mailers to Facebook ads and sponsored tweets.

David Keating, the president of the Center for Competitive Politics, which favors increased deregulation in elections, sees this as a positive development.

“Whenever there’s more speech that means there’s more information for voters,” says Keating, adding that such information helps “drive” voters to the polls.

Challengers, in particular, he continued, are generally helped “when there’s more money spent informing people about the incumbent’s record.”

But Michael Malbin, co-founder and executive director of the Campaign Finance Institute, a think tank based in Washington, D.C., doesn’t agree the proliferation of new groups has been a welcome change.

“Non-party groups are unaccountable,” Malbin says. “It’s better to have a system in which the voters can hold the candidates and their parties accountable for what they do.”

Dave Levinthal contributed to this report.