(Photo: Erin Vermeulen / Flickr)Dark money groups flooded Albuquerque’s airwaves in August, aiming to sway a hotly contested U.S. Senate race by making more than half the political ad buys on top TV stations.

That fact, gleaned through a review of TV station political ad records now available in our Free the Files news application, highlights the role that unlimited anonymous money is playing in this year’s election.

Our analysis of a month of ad orders in the Senate race between Republican Heather Wilson and Democrat Rep. Martin Heinrich is possible because of a new Federal Communications Commission rule requiring major-market affiliates of ABC, CBS, Fox and NBC to upload political ad files to a government website.

In statements to ProPublica, the campaigns of Heinrich and Wilson blamed each other for relying on dark money.

Wilson campaign spokesman Chris Sanchez accused “environmental extremists” of pouring money “into New Mexico to falsely attack Heather Wilson because they know her opponent, Congressman Heinrich, supports their radical agenda.”

Heinrich campaign spokeswoman Whitney Potter accused “corporate special interest groups” of spending millions in secret money to support Wilson “because they know she will support their misplaced priorities that put the wealthy special interests ahead of middle-class families in New Mexico.”

The Senate race has attracted national attention because, with incumbent Democratic Sen. Jeff Bingaman retiring, it is a rare open seat. The race was considered tight earlier this year. After a summer of heavy spending by outside groups on both sides, Heinrich is now the favorite.

In August, while Wilson’s campaign contracted to spend about $512,000 on ads in Albuquerque, four prominent conservative groups booked almost $658,000 of ads attacking Heinrich, station records show.

That means about 56 percent of the ad orders on the Republican side came from groups that don’t disclose their donors, including Americans for Prosperity, founded by billionaire brothers David and Charles Koch, and Crossroads GPS, launched by GOP strategist Karl Rove. Campaigns are required to report their donors.

Heinrich, who as a congressman has called for donor disclosure and campaign-finance reform, booked an estimated $246,000 worth of ads in August. The Democratic Senatorial Campaign Committee, which also reports its donors, chimed in with another $74,000.

But nonprofits on the Democratic side spent an additional $288,000 on ads criticizing Wilson, about 47 percent of the money spent on ads overall.

The liberal dark money groups included a coalition of environmental organizations and the Citizens for Strength and Security Fund, which appears to be a successor to a nonprofit active in the 2010 election.

The spending figures are estimates because most of the files uploaded to the FCC website are ad orders. Sometimes, ordered ads never run because of changes in programming. The numbers also are not comprehensive; other TV stations in the Albuquerque market besides affiliates of the major networks do not have to put political ad files online until 2014.

While the FCC files have long been public, they were previously kept on paper at TV stations and were largely inaccessible. The files capture certain spending not reported to the Federal Election Commission and offer a detailed look at how campaigns and outside groups are spending ad dollars, including how many ads have been ordered, which stations are running them, the programs they run on, and how much they cost.

The ad spending in Albuquerque shows that nonprofit social welfare groups are playing at least as significant a role this election cycle as super PACs, which can also accept unlimited donations but must report their donors. Not a single super PAC reported buying ads in August on the top stations in the Albuquerque market, the FCC filings show.

Some of the most prominent conservative social welfare nonprofits signed up to support Wilson, producing ads labeling Heinrich an out-of-control spender.

“Big Washington spending is not helping New Mexico. And the more money Martin Heinrich is spending is part of the problem,” a narrator in a Crossroads GPS ad says. Pointing to Heinrich’s support for the stimulus, the ad claims he voted to send $2 million to California to collect ants and $300,000 to Texas to study weather on Venus.

The group ordered about $166,000 in ads in Albuquerque in August, TV station filings show.

Unlike most candidates Crossroads is helping around the country, Wilson has a direct connection to the group. After she left Congress in 2009, she sat on Crossroads’ board for a six-month period ending in February 2011, according to her financial disclosure form.

In that role, “she attended board meetings, wrote an op-ed on defense policy, and provided general guidance, as all Crossroads board members do, on the organization’s activities and policies,” said Crossroads spokesman Jonathan Collegio.

Sanchez said Wilson does not currently have an “existing relationship or communication with Crossroads GPS.” Outside spending groups such as Crossroads are not allowed to coordinate directly with candidates.

Like the Crossroads ad, another pair of August ads funded by anonymous money labeled Heinrich an irresponsible spender. The American Future Fund, the conservative Iowa nonprofit, signed up to spend almost $97,000 on ads. Americans for Prosperity ordered almost $328,000 in ads in August.

The U.S. Chamber of Commerce, the only trade association spending money in Albuquerque in August, spent more than $67,000 on ads criticizing Heinrich.

Heinrich’s campaign has seized on the outside money on the conservative side even as he has benefited from dark money spending by liberal groups.

Last week, his campaign put out an ad featuring TVs playing conservative attack ads arriving at an airport luggage carousel. “Here they come,” the narrator says. “The special interests are here to distort Martin Heinrich’s record.”

Heinrich has also supported a bill, which has failed twice in Congress, to require outside spending groups to disclose their donors for political ads. In March, he sent a letter to the FCC urging it to swiftly implement greater transparency measures in disclosing who paid for political ads.

Nonetheless, a coalition of environmental groups including the League of Conservation Voters and the National Wildlife Federation Action Fund, has spent more than $1 million supporting Heinrich, including an ad accusing Wilson of being too cozy with polluting corporations.

In August, the coalition put in orders for more than $70,000 for TV ads in Albuquerque. (Most of the environmental groups’ spending took place earlier in the summer, before the FCC required TV stations to put political ad files online.)

On Tuesday an official from the League of Conservation Voters sent out a press release claiming the groups’ spending had decisively turned the race in Heinrich’s favor.

Another group, the Citizens for Strength and Security Fund, ordered about $218,000 in commercials to aid Heinrich in Albuquerque in August. Its ad says that Wilson is “promising more tax giveaways for millionaires”:

So what is the Citizens for Strength and Security Fund? Its website says it is a social welfare nonprofit formed in 2011 to strengthen the country and make the middle class more secure. Yet the site uses the same clip art, cites the same issues, and repeats much of the language as a now-defunct website for a similarly named group, the Citizens for Strength and Security Action Fund, or CSS Action Fund, that spent millions on ads supporting Democrats in the 2010 election.

A ProPublica story in August detailed how some social welfare nonprofits pop up for elections and disappear, only to re-form later, always staying a step ahead of the IRS. ProPublica found that some groups, including the CSS Action Fund, never applied to the IRS for recognition of their nonprofit status.

A March 2 letter in the FCC filings from Albuquerque says the Citizens for Strength and Security Fund is run by Lora Haggard, the chief financial officer for John Edwards’ campaign in 2008. The other officer named is Jeremy Van Ess, another longtime operative who works for Hilltop Public Solutions, a Beltway consulting firm that supports Democratic causes. The two people listed as running the CSS Action Fund (the earlier nonprofit) worked for Hilltop.

Haggard didn’t return calls for comment. Van Ess confirmed the group’s spending in New Mexico and said it had not applied to the IRS for recognition of its tax status because it was not required to do so. He declined to answer any other questions about Citizens for Strength and Security.