The House Democratic push to roll back the controversial Supreme Court decision loosening restrictions on political spending remains snagged on objections from the gun lobby.

Facing a closing window for action, Democratic leaders driving the measure are working to draft an exemption that will satisfy the National Rifle Association without gutting the whole package. But leaders face other concerns about the measure from some of their most politically vulnerable Members, who are anxious about backing a bill strongly opposed by the U.S. Chamber of Commerce if it is going to die in the Senate.

The need, the bill’s champions say, is urgent: Unless lawmakers establish a new disclosure framework for political spending, candidates could see money from anonymous outside groups flood their campaigns. The bill — officially the DISCLOSE Act — comes after a divided Supreme Court ruled in Citizens United v. Federal Election Commission to strike down many restrictions on televised political advertising.

Worries about the bill’s path forward were aired Wednesday morning when freshman Democrats sat down for their weekly breakfast with Speaker Nancy Pelosi (Calif.) and other leaders. Freshman Rep. Betsy Markey (Colo.) asked Rep. Chris Van Hollen (Md.) — the architect of the bill and a member of leadership as both Assistant to the Speaker and chairman of the Democratic Congressional Campaign Committee — about the status of the Chamber of Commerce’s opposition, sources in attendance said. Van Hollen explained that the chamber would always be opposed to the bill.

Freshman Reps. Frank Kratovil (Md.) and Paul Tonko (N.Y.) questioned the measure’s prospects in the Senate. The response from Democratic top brass: Senate Democratic leaders need the House to pass the bill to give it the momentum to move in their chamber.

“Number one, this is going to be a priority” for Senate Majority Leader Harry Reid (D-Nev.), Van Hollen said. “Number two, this bill stands on its own merits. … This is a positive for people. You get to go home and say, ‘I want you the voter to know who is spending money to influence elections.’ If a Member of Congress cannot run positively with that message, they need to improve their communications skills.”

Tonko, who is not vulnerable in November, said in an interview that he supports the package and would “vote for it if it were on the floor this afternoon.”

“My questioning about the Senate isn’t a condition for my support,” he said. “I was asking, ‘Is there hope to get this done?’ Because I believe so much in the bill, I want to see it brought to completion.”

Others are less enthusiastic. For some politically shaky Members, a vote for a bill the Chamber of Commerce has pledged to score would amount to a needless, self-inflicted wound if the package goes nowhere in the Senate. “Everything is different if we know something is actually going to happen in the Senate, rather than just having our guys thumbing outside groups in the eye,” a top aide to one vulnerable Member said.

Either way, leaders know they face a pro-gun majority in the House and need to accommodate the NRA before they can bring the bill to the floor. The gun lobby has objected to the bill’s provision requiring a group to identify its top donors in its political ads, charging it would force the group to turn its membership list over the government. Rep. Heath Shuler, the North Carolina Democrat who is a gun rights advocate and a co-sponsor of the package, has drafted a change that would exempt the gun lobby — and all other groups organized under 501(c)(4) of the tax code — from the disclosure requirements in the measure.

But House leaders and government reform advocates counter that the amendment is too broad. “It becomes the loophole that eats the whole purpose and intent of the legislation,” said Meredith McGehee, policy director of the Campaign Legal Center.

So leaders are looking for ways to narrow the exemption. “We’re moving along as fast as possible,” Van Hollen said. “It is just, from a drafting perspective, a complicated thing to do.” The point, Van Hollen added, is to “make sure fly-by-night organizations can’t hide the money. And that’s our goal right now, to make sure we do that in an effective way. … This is not just an NRA discussion.”

Indeed, leaders are still in negotiations with the AFL-CIO — and groups such as the Sierra Club and the Alliance for Justice — about the possibility of tweaks. “There are a number of very legitimate concerns that have been raised by (c)(4) and other organizations,” House Majority Leader Steny Hoyer (D-Md.) told reporters Wednesday morning. “They are not hiding anything, but they have large membership rolls, and they want to know exactly what this is going to mean to them.”

Leadership sources said an outside chance remains that the measure could move this week, though it is more likely to hit the floor next week. “I believe we are in a position to get a strong disclosure bill passed in the House,” said Fred Wertheimer, president of Democracy 21, a political reform group. “But it still depends on what happens in the next few days before the bill goes to the House floor.”