In 2002 former Defense Secretary Donald Rumsfeld once flippantly described connections between Saddam Hussein and Al Qaeda terrorists by saying, “There are known knowns; there are things we know that we know. There are known unknowns; that is to say, there are things that we now know we don’t know. But there are also unknown unknowns; there are things we do not know we don’t know.” Little did Rumsfeld know that his remark would be the most accurate description for a murky midterm election eight years down the road.

The 2010 midterm election is filled with both “known unknowns,” outside groups raised and spent $126 million on elections without disclosing the source, and “unknown unknowns,” we don’t know what those undisclosed donors want. We do know one thing: the Supreme Court’s Citizens United ruling allowed this election to be the costliest and least transparent midterm in recent history.

The impact of Citizens United can be judged by simply following the money. The $126 million in undisclosed money represents more than a quarter of the total $450 million spent by outside groups. Add the $60 million spent by groups that were allowed to raise unlimited money, but still had to disclose, to the undisclosed money and the total amount of outside money made possible by the Citizens United ruling reaches $186 million or 40 percent of the total spent by outside groups.

The outside groups taking advantage of the Citizens United ruling are largely tilted towards the Republicans. Republican groups raising unlimited money and disclosing their donors spent $35.7 million, $11 million more than their Democratic counterparts. By a nearly six to one margin Republicans outspent the Democrats among groups that failed to disclose the source of their money ($59 million to $10 million).

Click to see the top 20 outside groups and how they fared in the 2010 elections

This heavy partisan tilt in outside spending aided the Republicans in expanding the playing field and likely helped them exceed predictions for House seat pickups.

According to a report by Politico’s Jeanne Cummings, the Republican outside groups coordinated their spending, maximizing their ability to influence the elections with a massive wave of spending. Cummings also reports that the National Republican Congressional Committee (NRCC), which was at a serious monetary disadvantage to the Democratic Congressional Campaign Committee (DCCC), took an unprecedented step by disclosing their ad buy strategy to the public, thus allowing the Republican outside groups to coordinate their spending with the party committee. The party committee is forbidden to coordinate with outside groups. A new loophole in federal election laws was forged when the NRCC publicly revealed their ad strategy.

Crossroads GPS, a group associated with former Bush political director Karl Rove, spent 75 percent of their money on races where the Republican candidate won. The group spent $4.4 million, the most they spent in any race, opposing Democratic candidate Alexi Giannoulias in the closely fought Illinois Senate race. Giannoulias lost the race to Mark Kirk by two percentage points. GPS does not disclose their donors and could only exist in a post-Citizens United world.

The group also spent money in tight House races where Republicans have pulled off victories or appear to have won. Democratic incumbent Jim Costa looks to be headed to a defeat in California’s 20th district. Crossroads GPS spent over $300,000 against Costa, who is trailing by less than three percentage points. The group spent another $300,000 against Texas Rep. Ciro Rodriguez, who lost by five points to his Republican challenger.

The other Republican groups, including American Crossroads, another Rove-linked organization, spent most of their money on races that Republicans won. American Crossroads spent significantly on key House races that Republicans picked up including Florida’s 22nd, New York’s 20th district and Texas’ 17th district. Republicans also seem poised to win a close victory in New York’s 25th district where American Crossroads spent over $400,000 to defeat Rep. Dan Maffei.

Click to see the top 20 outside groups and how they fared in the 2010 elections

Democratic-linked groups, including the big labor unions AFSCME, NEA and SEIU, did not fare well in the election. AFSCME, the union representing public sector workers, spent 85 percent of their money–$6.51 million–on races where the Democratic candidate lost. NEA, the National Education Association, was the most successful among Democratic groups in where it placed the majority of its money. The group spent 68 percent of its money on races where Democrats won.

Prior to the November 2nd election Congress sought to require outside groups to disclose their money by voting on a bill known as the DISCLOSE Act. The DISCLOSE Act would have required many of these groups to disclose some of their top donors to the public, reducing the trend begun by Citizens United towards less transparent elections. Already groups aligned with the Tea Party are stating their opposition to any attempt at increasing disclosure in the campaign finance system.

It is unclear whether the lame duck 111th Congress or the 112th Congress, with Republicans in charge of the House of Representatives, will move to pass a disclosure bill for this outside spending. The trend towards more “unknown unknowns” looks as though it will increase in the 2012 election and beyond.