Facing revolt from two corners of their rank and file, House Democratic leaders are punting on a campaign finance measure so they can continue making changes aimed at building support. The eruptions from members of the Congressional Black Caucus and the fiscally conservative Blue Dog Coalition came after a leadership-authored tweak to the package exempted the National Rifle Association from new disclosure requirements, prompting heated protests from an array of business groups and left-leaning nonprofits.Speaker Nancy Pelosi (D-Calif.) and her team huddled late Thursday afternoon with the CBC and, later, with the Blue Dogs to try to work through their concerns. But participants in both meetings said they broke without resolution. The package, called the DISCLOSE Act, would roll back the Supreme Courts split decision in Citizens United v. Federal Election Commission that lifted political spending limits on corporations and unions. The bill would bulk up disclosure, political coordination and disclaimer requirements, and it would impose new limits on political involvement by government contractors and foreign governments.It has become a top priority for Pelosi, and leadership aides described her as angry about the latest holdups. The top House Democrat played down the complications at her weekly media briefing and projected confidence about its prospects. Its fundamental to our democracy, she said. We will pass it.But the majority postponed a Rules Committee markup of the bill that had been set for Thursday afternoon, then canceled it, before scotching Friday votes altogether. The problems started when leaders realized the NRAs opposition would imperil the bill. They decided last week that a proposed fix from Rep. Heath Shuler (D-N.C.) that exempted all 501(c)(4) organizations the section of the tax code under which the gun lobby is organized went too far. In an attempt to narrow Shulers amendment, they crafted a tightly qualified exemption for any groups that have more than 1 million members spread across all 50 states and that receive no more than 15 percent of their funding from corporate or union sources. The problem with that fix was that no other group besides the NRA appeared to meet the standard, and other affected groups across the ideological spectrum cried foul. They refused to relent after leaders announced on Thursday their intention to lower the exemptions membership threshold to 500,000.CBC members, many of whom hail from urban areas plagued by gun violence, balked at voting for a bill tailored to protect the gun lobby. Rep. Donna Edwards (D-Md.) said she and her colleagues were trying to develop a new strategy for dealing with affected groups, so you apply across the board in a more even-handed way the treatment of these organizations and entities.The Blue Dogs, meanwhile, were focused on Senate prospects for a bill that has drawn intense criticism from business groups, including the U.S. Chamber of Commerce. With many Blue Dogs facing tough re-election battles, the group wants to avoid a vote that would antagonize the business community if the bill is only going to stall in the Senate.