Campaign 2012 marks the debut in American politics of super PACs, or "super political-action committees," empowered to raise unlimited sums of money from corporations, unions, and individuals and spend it for or against candidates – and they are already having a dramatic impact.

In this election cycle so far, 900 reported super PACs have spent more than $318 million to influence presidential and congressional races, funding a blitz of advertising in the primary states, swing states, and nationwide. Notably, more than 70 percent of all super PAC ads have been negative.

News organizations, public interest groups, and bloggers have covered super PACs extensively, especially in a bid to identify donors and their interests. Groups such as The Sunlight Foundation, The Center for Public Integrity, and the Center for Responsive Politics are tracking super PAC spending down to the dollar. The top 1 percent of donors (105 people) have contributed 58 percent of all super PAC funding, mainly directed to help conservatives.

Decoder has compiled a report on the seven top super PACs – the organizations that have spent the most and still have the most money in the bank – the candidates they support, and the donors behind them. Here is the bigger picture on the new groups funding this election.