The provision was in a bill that had little hope of GOP support because it sought to restore a ban on certain semi-automatic weapons, a non-starter for many in the GOP.
The party also faces an extra complication because many of its incumbent senators, including a handful of them up for re-election this year, hail from red states where any form of gun-control legislation will be less popular.
A semi-automatic rifle fires one round per squeeze of the trigger.
Yet if society has agreed that automatic weapons should be banned - as even many pro-Second Amendment groups do - it makes no sense to allow the sale of a part that circumvents this long-standing prohibition.
The fact that weapons like the AR-15 can be retrofitted with bump stocks legally is wholly indefensible when great carnage can be inflicted so quickly.
The device causes the gun to buck back and forth, repeatedly "bumping" the trigger against the shooter's finger.
"A semi-automatic rifle with a bump-fire stock on it is not an illegal machine gun", she told CBS Evening News.
No matter what happens, Congress keeps refusing every effort at even moderate gun controls.
Thursday's sudden endorsements of controls came nearly simultaneously from the NRA and the White House.
But Paddock didn't need to be accurate when firing into a crowd of 22,000 people packed into a crowded concert venue.
No fear, maybe, because Feldman had no knowledge of the existence of bump stocks until now anyway.
The Republicans responded by saying that they would consider banning the tool despite years of resisting any gun control laws to be enforced in the country. Here are three items that are still legal and that gunowners can use to modify their semi-automatics, along with a work-around.
Given that there were no breakthroughs on gun legislation after other recent mass shootings, including the killings of 20 children and six teachers at Sandy Hook Elementary School in 2012, conservative support for a ban on bump stocks has buoyed some liberals.
On Thursday, the National Rifle Association joined the Trump administration and top congressional Republicans in seeking to regulate bump stocks. A Gallup poll released late past year found that support for a ban on semi-auto assault rifles was at an all-time low, with just 36 percent of Americans in support of it.
Part of Paddock's plan, officials said, was the modification of weapons from semi-automatic guns into fully automatic ones that could rapidly dispose of bullets at a pace-10 shots a second-and so could mow down concertgoers before they could make their escape from the Route 91 Festival below.
This general unawareness that bump stocks even exist might help explain the rare bipartisan consensus on gun reform this week.
Jeremiah Cottle, a US Air Force veteran, invented the bump stock device after having the idea while out shooting with a friend.
In Massachusetts, weapons that fire multiple rounds "by one continuous activation of the trigger" are restricted.
Texas Republican Sen. John Cornyn said Wednesday, "I own a lot of guns, and as a hunter and sportsman, I think that's our right as Americans, but I don't understand the use of this bump stock".
Reports emerged on Thursday that Paddock may have targeted other sites for attack in Chicago or Boston before the Las Vegas shooting. "They want to go out and limit the rights of gun owners", Scalise said.
Slide Fire, one of the leading manufacturers of the devices, says on its website that the company "has not been notified by any individual state that our products conflict with any state laws" since its founding in 2010.
"My staff takes their job very seriously, and if there were any red flags during this transaction, like any other, it would be halted immediately", said David Famiglietti of New Frontier Armory in Las Vegas, where Paddock purchased a shotgun and a rifle this spring.
