For years, political advertisers have benefitted from a loophole big enough to drive a $10 million-dollar political campaign through. "Issue ads" that don't explicitly ask for a vote for or against a candidate, and don't run immediately before the election, don't have to be disclosed to the Federal Election Commission.

But new rules requiring about 15 percent of the country's broadcast TV stations to disclose these ad buys online are beginning to pull the veil off this secret spending. And, the documents help make clear, the line between "issue ads" and the endless campaign is vanishingly thin. Sunlight and other partners, including Free Press, are compiling the disclosures on our Political Ad Sleuth database.

Less than a week after the presidential election, the American Petroleum Institute was on the air with a new TV ad campaign warning against the economic dangers of new energy taxes — one of the possible revenue raisers being discussed as the nation hurtles toward the so-called "fiscal cliff." The Simpson-Bowles bipartisan commission recommended a 15-cent-a-gallon gasoline tax hike to help offset transportation infrastructure costs.

In a Nov. 13 press release, the API said the ads would "help educate Americans" and "encourage members of Congress" by running the ads "in selected states". What the press release did not provide were the names of the states or what they have in common: they are all politically red or purple states with Democratic senators who are up for reelection in 2014.

The ads, now posted on the API's website, reveal that the trade group cut two versions: The more positive  lauds two senators in the oil-producing states of Louisiana (Mary Landrieu) and Alaska (Mark Begich) saying, for example, "Good thing Sen. Mark Begich is fighting for economic growth. He knows job killing energy taxes hurt alaska's economy."

For five Democratic senators up for reelection in right-leaning and swing states, a slightly different version of the ad sets up gas taxes as a test: "Senator Mark Udall can make energy a big part of improving our economy. He can choose economic growth and american jobs, not slow them with job killing energy taxes." Also targeted are Sens. Mark Warner, D-Va., Mark Pryor, D-Ark., and Tom Udall, D-N.M. and Kay Hagen D-N.C.

The API spent at least $200,000 on ads in the Denver market alone, according to FCC documents collected by Political Ad Sleuth. The ads began running the week of Nov. 12 and are scheduled to continue through at least Dec. 2. It's unclear how much the group spent running positive ads because none of the stations in Alaska or Louisiana are required to put their political files online. Some documents are available showing ad buys in New Mexico, Virginia and North Carolina, though Sunlight researchers haven't yet waded through this data.

Whatever is spent on this campaign, it's just one drop in a very large barrel. The oil and gas lobby spent $56.3 million on political expenditures–including $14 million in lobbying–in 2010 alone, the most recent year tax documents were available. "Issue ads" against members of congress up for reelection would appear to be just one tool in the API's very extensive arsenal.

The API didn't respond to calls for comment, but the senators are taking note. In Colorado, where spots from both the API and several big unions have been airing, "we've already heard from constituents concerned that we're already running ads," said Mike Saccone, a spokesman for Colorado Sen. Mark Udall. Saccone declined to speak about campaign issues–he's a government employee and barred from campaigning during work hours–but he said that with the election roughly two years away a campaign spokesman hadn't yet been hired.

Regardless of how much interest groups spend staking out their claims, the ads aren't helping fix the problem, Saccone said. The Colorado senator "has been clear that there needs to be flexibility when dealing with the fiscal cliff — whether it's oil and gas or unions — rigidity and a failure to come together and compromise is frankly how we got into the situation."