The Supreme Court’s Citizens United ruling opened up a massive hole in the disclosure regime governing campaign spending. According to a new report by the group Public Citizen, that hole is as wide as many feared. Only 32 percent of the independent groups spending on the 2010 midterm elections are disclosing the names of their donors to the Federal Election Commission. This is down from 98 percent in the 2004 election.

Congress, backed by President Obama, is seeking to close this hole by passing a bill known as the Disclose Act. The Disclose Act passed the House of Representatives, but has stalled in the Senate.

This weekend the President called on Congress to plug this disclosure hole and pass the Disclose Act, “We’ve tried to fix this with a new law – one that would simply require that you say who you are and who’s paying for your ad.  This way, voters are able to make an informed judgment about a group’s motivations.”

The New York Times points out what happened to the Disclose Act when it was blocked in the Senate earlier this year, “The Citizens United decision, paradoxically, supported greater disclosure of donors, but Senate Republicans have filibustered a bill that would eliminate the secrecy shield.”

At the time, Sunlight’s Lisa Rosenberg wrote, “by opposing transparency, it seems that Senate Republicans and their special interest allies are trying to boost their own fortunes in November by ensuring that Republican-leaning corporate coffers can be opened up to help Republican candidates without leaving any fingerprints behind.” As the decrease in disclosure has increased, largely driven by Republican-oriented firms, we can see this outcome already playing out. But who’s to say that the next election won’t be driven by groups backing Democratic candidates and policies?

The Senate is considering taking the Disclose Act back up, possibly as a stripped-down, disclosure-only bill. Even though it’s too late to fix the transparency hole blasted into our elections by the Supreme Court, the Senate can still ensure that the next election won’t be as unaccountable as this one by passing a bill that requires that these firms report their donors.

The New York Times’ The Caucus blog features a graphic highlighting the declining level of disclosure post-Citizens United.