DENVER -- Amidst reports of a torrent of some $3.5 million in spending, much of it from out of state, on today's recall elections for two Colorado state senators who voted in favor of stronger gun control laws, it appears all but certain that the actual tab will be much, much more. That's because of the big black hole even intrepid journalists fall in when trying to put together solid numbers on how much is being spent here.

A number of major spenders in the race are not required to report their contributors or expenditures to the Colorado Secretary of State's office. Because the races are considered a ballot question, much of the spending is classified as issue advertisements as opposed to supporting or opposing a candidate, and does not trigger official reporting requirements.

Consider Americans for Responsible Solutions, the group founded by former Rep. Gabrielle Giffords, D-Ariz., to advocate for stronger gun laws. The group has produced several ads, captured here by Sunlight's Ad Hawk tool, supporting State Senate President John Morse of Colorado Springs and Sen. Angela Giron of Pueblo, both Democrats.

But the group, which operates both as a 501(c)4 charity and as a super PAC, does not meet the definition of a "committee" in Colorado and therefore is not required to report either contributions or expenditures. The group did not return a request for comment by the time of this posting.

Same with National Association for Gun Rights, which produced this anti-Morse ad. The organization has both a 501(c)4 charity and a PAC. Danielle Thompson, a spokeswoman for the group, said that it had spent about $100,000 on that ad and another produced by the group's local affiliate, Rocky Mountain Gun Owners. The group also produced radio ads, sent emails, and engaged in other activities in support of the recalls. However, the group does not report these expenditures because they are considered issue advertisements.

In contrast, at the federal level, even 501(c)4s charity groups must report some spending on elections during a certain time frame.

While local broadcast stations are required to keep paper files of advertisements bought by political groups, the stations in Colorado Springs and Pueblo, where the two senators targeted for recall are based, are not required to post this information online by the Federal Communications Commission, since they are not among the top 50 media markets in the country. So while reporters could rifle through those paper files to get some information about spending by such groups, it would require a lot of leg work to scan the documents and build a database.

Other nonprofit groups that have been active in the race but have not reported any spending are Koch-backed Americans for Prosperity, and Free Colorado, both in favor of the recalls, and VoteVets.org, which opposes them.