Multiple bills to ban bump stocks are sitting in limbo on Capitol Hill. GOP leaders and the NRA suggested the ATF should regulate bump stocks, even though the agency has in the past said it cannot ban such items outright.

WASHINGTON – After the mass shooting in Las Vegas, the deadliest of its kind in modern history, there was a spur of energy by lawmakers on Capitol Hill to move forward on one very specific gun control measure – a ban on bump stock devices that are used to increase the rate of fire on semiautomatic rifles, which the Las Vegas shooter had attached to a dozen of firearms inside his hotel room.

But several weeks later, the issue has faded from both headlines and the agenda in Congress, despite a bipartisan bill to ban the bump stock devices that a number of Republicans signaled they could support.

Reps. Seth Moulton, a Massachusetts Democrat, and Carlos Curbelo, a Republican from Florida, introduced a bump stock ban in the days following the attack. A similar bill was brought forth by Democrats Mike Thompson and David Cicilline, but without Republican support. The Moulton-Curbelo bill had an additional nine Republican cosponsors.

House Speaker Paul Ryan even signaled he would be open to discussing the issue, telling conservative pundit Hugh Hewitt, “Clearly that’s something we need to look into.”

But Ryan distanced himself from the issue after the National Rifle Association, a top donor to his campaigns over the years, called for a regulatory assessment of bump stocks as opposed to a legislative one.

"We think the regulatory fix is the smartest, quickest fix," Ryan said in an October 11 press conference.

But the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) has made it clear that it cannot ban bump stocks, which was noted in a 2013 letter to Colorado Rep. Ed Perlmutter.

"We remain committed to the security of our Nation and the fight against violent crime," wrote Assistant Director for Public and Governmental Affairs Richard Marianas. "However, bump-fire stocks that do not fall within any of the classifications for firearm contained in Federal law may only be classified as firearms components. Stocks of this type are not subject to the provisions of Federal firearms statutes. Therefore, ATF does not have the authority to restrict their lawful possession, use, or transfer."

The ATF did not respond to a request for comment on an updated policy regarding a potential ban on the sale, transfer, or use of bump stocks.

Now, almost a month after the shooting, any talk of a bump stock ban has left the halls of Congress.

Curbelo told Business Insider on Monday that his bill "will come back" because he "highly highly" doubts the ATF will be able to "change their regulations in a credible way."

"I think interest groups and maybe some members have convinced others to hold back for some time," said Curbelo in reference to the NRA's position of leaving it up to the ATF. "I think that's a mistake."

"A lot of the attacks that have been leveled against the bill are completely false," Curbelo added. "The bill is very clear that it bans bump stocks and devices like it that are designed to circumvent existing laws."

In terms of what Ryan and the rest of the Republican leadership are planning, Curbelo said, "I don't think they've thought that far" and that their focus is on overhauling tax code at the moment.

"So we're gonna keep demanding a vote and I think there will be more pressure to do that once, in my opinion, the [ATF] fails to adequately respond - because they've admitted that they're unable to do so already," Curbelo said.

A senior GOP leadership aide told Business Insider that House leaders and relevant committees are still discussing the best course of action and communicating with the ATF about what options are on the table, noting Ryan's preference to have bump stocks regulated by administration officials instead of Congress.

But the slow pace at which any action on gun control happens is a bit demoralizing for lawmakers who have been set on seeing the slightest change.

Sen. Chris Murphy, the Connecticut Democrat often at the forefront of pushing for increased gun control, told Business Insider that "it's difficult with a 24-hour news cycle to keep attention on the policy solutions in the aftermath of these murders."

Murphy added that what it boils down to is a lack of regular order and an ability to work in a bipartisan fashion in Congress, which prevents anything from even having a debate.

"I mean this issue wouldn't go away if we had any kind of regular order," he said. "But the Senate is fundamentally broken."