WASHINGTON – The nation’s leading gun control group is sharply criticizing a carefully-crafted exemption to National Rifle Association on a campaign finance bill designed to curb the impacts of the controversial Supreme Court ruling this year.

"It defies logic for Congress to want to shine a light on the role of money in politics by requiring disclosure of those putting in the most money, and then exempt the advocacy group putting in the most money," Paul Helmke, president of the Washington-based Brady Center to Prevent Gun Violence, told Raw Story.

Democrats this week modified their DISCLOSE Act proposal – which places stringent disclosure requirements on organizations engaging in political advocacy or campaign-related activities – to exempt groups in existence for a decade with at least one million paying members and whose political endeavors aren't funded by corporations or unions.

The one formidable group that fits this description is the NRA, which has apparently dropped its opposition after mobilizing against the effort in recent weeks. The gun rights group has dished out over $17.5 million to lobby Congress since 1990, according to the Center for Responsive Politics, dwarfing that of most lobbying groups and certainly gun control advocates.

"If the Democratic leadership allows this NRA exemption to go forward just because it needs the votes of those Democrats who receive money from the NRA, they will just be reinforcing the growing cynicism in this country about our political system," Helmke said, arguing that it "certainly doesn't make sense to do this for the big money fat cats."

The Brady Center, of course, has narrower goals than Democratic leaders, who deemed this concession a necessary price to pay for tempering the abilities of corporations to freely mold elections and public policy to their liking.

"Reform in Washington is never easy – that is why powerful special interests are mobilizing against our effort to shine a light on campaign-related spending," said Rep. Chris Van Hollen (D-MD), the bill’s chief sponsor, in a statement.

"Our key objective in responding to the Supreme Court’s radical ruling in Citizens United has been to increase transparency and disclosure, and the final bill achieves that goal," he added.

The Brady Center has co-signed a letter to House Speaker Nancy Pelosi (D-CA) with dozens of other progressive groups pledging to oppose the measure as a result of this deal, which complicates matters for Democrats working to cobble together the necessary votes against stiff Republican opposition.

The NRA stonewalled liberal criticisms that it could be used to funnel political attack money from groups that aren't covered under the exemption. "One polite word: BUNK," NRA spokesman Andrew Arulanandam e-mailed Ben Smith of Politico. "The language of the exemption says that we can't spend any corporate revenue on campaign activity."

Many campaign finance groups such as Public Citizen, Common Cause, Campaign Legal Center, and Democracy 21 say they support the legislation on balance, viewing it as a step towards greater corporate transparency.

House Democratic leaders intend to vote on the measure this week.