What we’ve learned so far in the short primary season is that political advertising still has a major impact. Newt Gingrich was obliterated in Iowa and Florida by a negative ad attack, and that also played a role in Mitt Romney losing his grip on South Carolina. While polling indicates that the President has benefited from the negative ad surge, the guns have for the most part not been trained on him. And when they do, it will be coming from secret sources.

More than a third of the advertising tied to the presidential race has been funded by nonprofit groups that will never have to reveal their donors, suggesting that a significant portion of the 2012 elections will be wrapped in a vast cloak of secrecy.

The bulk of the secret money spent so far has come from conservative groups seeking to propel a Republican into the White House, advertising data shows. Millions of dollars in additional spending from both sides has poured into legislative races, such as the Senate contest in Massachusetts, that could help determine which party controls Congress in 2013.

The flow of funds is part of a wave of spending by outside groups that has quickly come to dominate the 2012 presidential contest, particularly by so-called “super PACs” that have few limits on their activities.

But unlike super PACs, politically minded nonprofit groups are under no obligation to disclose the corporations, unions or wealthy tycoons bankrolling their advertising, much of which is almost indistinguishable from regular political ads run by campaigns.

As much as this is a threat in the Presidential election, it’s probably much bigger for Congress. Barack Obama and Mitt Romney are going to have resources or the ability to gather them to challenge assaults from dark money sources. It’s unlikely that some random Democrat in a House district race will have the same ability. And there’s no question that SuperPACs and other groups will play in those races, with a close election expected and control of the House potentially at stake. We probably won’t even know about the crush of money in those districts until the election ends. And we’ll never know the identity of the fundraising sources.

As the FEC becomes more paralyzed and campaign finance rules more of a suggestion than the law, we’re going to see more and more of this. Corporations and wealthy donors have a path to virtually taking over elections. People power can only contest that so far.