As in super PACs, or political action committees, potentially massive political groups that will raise and spend unlimited amounts of money in support of candidates.

In the new, post-Citizens-United campaign era, corporations and unions can now spend money independently to back candidates, but the Federal Election Commission has ruled in recent regulatory decisions that corporations and unions can also donate unlimited amounts to political action committees that are dedicated only to independent expenditures (as opposed to direct donations to political campaigns).

Essentially, this means that corporate and union election spending can be aggregated, along with donations from individuals and other groups. Eliza Newlin Carney reports at National Journal:

Responding to questions from the anti-tax Club for Growth and a new Democrat-friendly political group dubbed Commonsense Ten, the FEC opinions spell out that corporations and labor unions may now make unlimited donations to independent expenditure committees -- that is, groups that weigh in on elections without coordinating with or donating directly to candidates...

"I expect you'll see an uptick in these kinds of groups," said Marc Elias, a partner at Perkins Coie and an attorney for Commonsense Ten. Indeed, the FEC advisory opinions appear to set the stage for a new generation of "super" political action committees that raise unlimited, previously-outlawed corporate and union money, while comprehensively reporting all receipts and expenditures. These groups must follow the same disclosure rules as fully-regulated PACs, but may not donate money to candidates.

Previously, donations to PACs have been capped at $5,000, and much political spending was curtailed under that system. Corporate money did make its way into elections, by way of CEOs and top executives donating $5,000 at a time to PACs, which would then spend unlimited amounts in independent-expenditure (not coordinated with campaigns, separate from campaign donations) ad campaigns. Citizens United eliminated that barrier, letting the money flow directly.

Now, corporate and union money can be pooled in supergroups, as Marc Elias suggests may happen more frequently. It's much easier to influence an election through independent spending, since direct donations to candidates are capped at a few thousand dollars, so perhaps gigantic independent-expenditure-only groups will proliferate into a new sort of independent political oligarchy, challenging the parties, the big unions, and the Chamber of Commerce in a Gigantomachia of soft money.