Already in this election cycle, nonprofit groups using the cover of "issue advertisements"—thinly disguised attacks or promotions of a particular candidate—have spent about $30 million on general election ads, according to a new study. But only about $4.4 million of buys have been disclosed to the Federal Election Commission.

That’s because the issue ads, also known as "electioneering communications," must be disclosed to the FEC only when they air on TV or radio in the weeks immediately preceding an election. It's a quirk in the election law that offers another way for deep-pocketed donors to influence votes without leaving any footprints.

Issue ads or electioneering communications are not covered by the same rules as campaign ads because they stop short of calling for the election or defeat of a particular candidate. But most won't fool most voters. Crossroads GPS, a group promoting GOP candidates and founded by strategist Karl Rove, launched an “issue advocacy initiative,” billed as costing $20 million, “to frame the national debate on jobs, the economy and the national debt,” according to a Crossroads press release. All of these ads criticized President Obama or Democratic senators that the group is trying to unseat. One national ad closed with the line, “There’s gotta be a way to take away President Obama’s blank check.” The ads also targeted five Democratic senators in fierce contests up for re-election: Claire McCaskill, D-Mo., Bill Nelson, D-Fla., Sherrod Brown, D-Ohio, Jon Tester, D-Mont., and Ben Nelson, D-Neb., who later decided not to run.

Why aren’t these ads required to be disclosed to the FEC?

All ad buys by third-party groups that expressly call for the election or defeat of a candidate must be disclosed to the FEC as independent expenditures. Electioneering communications, on the other hand, must be reported to the FEC only if they:

Fall within 60 days of a general election or 30 days of a primary or national conventions.

Air on TV or radio or via cable or satellite – so no Internet or print ads are covered.

Name a federal candidate.

Target voters in the candidate’s state or district.

Aggregate to at least $10,000 in a calendar year (when combined with other electioneering communications by the same entity)

What are we missing?

Groups that run electioneering ads within the FEC's disclosure window -- 30 days before a primary election or 60 days before a general election -- must provide the public with the following information about them:

The amount of the buy

The names of the candidates mentioned

The state and, if applicable, the district, where it’s airing

Who was paid to make the ad

The date of the expenditure and the date the ads hit the airwaves

The individual (or person within an organization) executing the buy

Why aren't outside groups required to disclose more?

Regulation of some issue ads by outside groups started in 2002, with the passage of the Bipartisan Campaign Reform Act, known as McCain-Feingold after it’s co-authors, Sen. John McCain, R-Ariz., and former Sen. Russ Feingold, D-Wis. The act defined electioneering communications and banned corporations and unions from making them. Thanks to recent court decisions, including Citizens United, the corporate and union ban has been lifted but the disclosure requirement still stands.

Paul Ryan, a lawyer at the Campaign Legal Center, a group pushing for stronger campaign finance laws, said McCain and Feingold deliberately limited the law's reach to avoid First Amendment challenges. Without the limited disclosure window, every ad that mentions a congressman or candidate would have to be reported to the FEC. If an ad about an upcoming congressional vote that mentions a lawmaker had to be dislosed as a campaign expenditure, the group behind the ad could challenge the rule as an unconstitutional limitation on free speech, said Bob Biersack, a senior fellow at the Center for Responsive Politics.

BCRA’s authors limited the regulation to TV and radio because that’s where most of the election spending was, Ryan said. And BCRA’s authors wanted to use a finite source of communications to maintain a scientific approach that could survive a court challenge, Ryan added. To craft their standard for electioneering ads, they used a study by the Brennan Center for Justice where students coded whether an ad’s primary purpose was election-related.

BCRA seemed to thread the needle, as the Supreme Court upheld the law in McConnell v. FEC in 2003.

New timeframe?

While Biersack, who used to work for the FEC, acknowledged that the current reporting windows are pretty arbitrary, he noted that advertising doesn't usually happen six months before voting, especially in congressional elections. Ryan, however, argued that times have changed since the late 1990s, when most ads were being run within 30 or 60 days of an election. He said campaigns have gotten longer -- an assertion that appears by be corroborated by the high-dollar issue ad campaigns cropping up early in this campaign cycle.

The Campaign Legal Center and the Sunlight Foundation back the 2012 DISCLOSE Act, which would widen the window requiring disclosure. For the presidential race, a nationwide disclosure window would open 120 days before the first caucus or primary. For congressional elections, any ad in the calendar year of the election would be disclosed.

Ryan said the law would comport with the views of the high court. “The Supreme Court has said repeatedly that disclosure is a pretty light burden on political players” and enhances democracy, he said.

Allen Dickerson, the legal director of the libertarian Center for Competitive Politics, argued the extension would have a chilling effect on speech, saying that makes half of a congressional term off limits for call-your-congressman ads.

That extension makes people less likely to run ads because they have to hire expensive lawyers to comply and you could guess wrong—you may not if a candidate is even vying for a seat that far in advance, and risk being investigated.

“I think the court is concerned about the creep of compliance costs and regulation,” Dickerson said.

It's small groups unable to navigate complicated rules that usually get fined, said Dickerson, citing a Colorado study showing that a larger percentage of campaign finance fines in that state hit small groups as opposed to well-organized 527 organizations.