Legislation aimed at blocking people on federal terrorist watch lists from purchasing firearms has been endorsed by President Barack Obama and congressional Democrats, and it prompted Donald Trump to call for a meeting with the National Rifle Association, a staunch opponent of further restrictions on gun purchases.
But many experts question whether the so-called "no fly, no buy" approach would be effective, noting that it would not have prevented several of the most grisly recent mass shootings in Orlando, Florida; San Bernardino, California; and Sandy Hook Elementary School in Newtown, Connecticut.
The reason: None of the attackers were among the more than 1.1 million people on the government's databases of suspected terrorists, including those with potential extremist ties banned from flying while under investigation.
The "no fly, no buy" legislation introduced by Democratic Sen. Dianne Feinstein of California has drawn support from those who favor additional restrictions on gun purchases. While discussions of the amendment generally refer to it as "no fly, no buy," it actually would cover far more people than the approximately 64,000 people on that list, FactCheck.org notes.
It also would cover people on the Terrorist Identities Datamart Environment, or TIDE, which included 1.1 million people as of December 2013, and the FBI's Terrorist Screening Database, of which the "no-fly" list is a subset.
This type of legislation shouldn't be the only effort at reducing gun violence, said Jon Vernick, co-director of the Johns Hopkins Center for Gun Policy and Research.
"In addition to efforts to prevent access to firearms for those on terror watch lists, we clearly need to also focus on broader polices — such as requiring a background check for every gun sale — intended to make it harder for a larger group of high-risk people to get firearms," he said.
But Craig Rimmerman, a professor of public policy and political science at Hobart and William Smith Colleges, said the bill could make a difference.
"Whether in the end it's going to prevent these kinds of assaults is unclear, but we have to do something in the meantime. There are a number of things we haven't tried yet including 'no fly, no buy,'" he said.
Feinstein is the primary sponsor of legislation that would empower the attorney general to block the sale of firearms and explosives to people suspected of terrorism involvement. A similar measure failed to move forward in the Senate late last year, blocked by the Republican leadership.
Senate Democrats ended their nearly 15-hour filibuster early Thursday after striking a deal with the GOP colleagues to vote on two gun control measures. Lawmakers will vote on whether to ban people on the government's terrorist watch list from obtaining gun licenses and expanding background checks to gun shows and internet sales.
Many of the frustrated Democrats who spoke throughout the night pointed to "no fly, no buy" as a starting point and rallying cry for reform.
"I'm prepared to stand on this floor and talk about the need for this body to come together on keeping terrorists away from getting guns … frankly, as long as I can because I know that we can come together on this issue," Sen. Chris Murphy, D-Connecticut, told lawmakers.
President Barack Obama, in his call Tuesday for "common sense" gun control measures, said "people with possible ties to terrorism who are not allowed on a plane shouldn't be allowed to buy a gun."
The "no fly, no buy" push comes amid growing congressional debate in the wake of the deadly shooting rampage in Orlando over the weekend by a lone gunman who officials say became radicalized over the internet and sympathized with ISIS. Forty-nine people were killed and at least 50 injured when the gunman, Omar Mateen, opened fire at Pulse, a gay nightclub.
Federal investigators looked into Mateen's possible terrorism ties in 2013, but later removed him from the FBI's watch list after finding no evidence he posed a risk. Under current federal law, however, even if he had been on that watch list, he wouldn't have been barred from purchasing a gun.
That fact has many Democrats and several Republicans, including presumptive Republican presidential nominee Donald Trump, up in arms.
According to FBI data, between 2004 and 2014, people on the terrorist watch list were involved in firearm or explosives background checks 2,477 times. At least 91 percent of the time, those firearms or explosives transactions were allowed to proceed, according to the Government Accountability Office.
Officials say it is difficult to track whether any of those weapons were used to commit terrorist acts.
Civil liberty groups and the National Rifle Association say one of the major concerns about blocking people on terror watch lists from buying guns is that people who were erroneously placed on the list could have their Second Amendment rights curtailed.
"The NRA's position on this issue has not changed," Chris W. Cox, executive director of the NRA's Institute for Legislative Action, said in a statement Wednesday. "The NRA believes that terrorists should not be allowed to purchase or possess firearms, period. Anyone on a terror watch list who tries to buy a gun should be thoroughly investigated by the FBI and the sale delayed while the investigation is ongoing. If an investigation uncovers evidence of terrorist activity or involvement, the government should be allowed to immediately go to court, block the sale and arrest the terrorist."
"At the same time, due process protections should be put in place that allow law-abiding Americans who are wrongly put on a watch list to be removed," Cox said.
Gun policy experts say the collective political will for broader reform just isn't there. The congressional fight in the wake of the 2012 shooting massacre at Sandy Hook Elementary School in Newtown, Connecticut, Murphy's home state, perhaps best illustrates where things stand.
In 2013, despite polls showing broad public support and a high profile push by the Obama administration, Senate Republicans and some Democrats stymied efforts at broad gun policy reform. Their votes scuttled efforts at an assault weapons ban and high-capacity ammunition magazines and a bipartisan bill on background checks.
Still, there has been some recent election year movement.
Sen. Rob Portman, a Republican from Ohio who is facing a tough re-election race, said Tuesday that he favors a ban on gun sales to individuals on a terrorist watch list as long as those mistakenly added to the list can be removed.
Last year, Portman opposed Feinstein's bill and instead supported alternative legislation proposed by Texas Republican Sen. John Cornyn that would have allowed officials to delay the transfer of a firearm to a suspected terrorist for 72 hours and ask a judge for probable cause to make the ban permanent if evidence showed that individual posed a threat.
On Wednesday, Trump said that he plans to meet with officials from the NRA about preventing people on the "no fly" federal terrorist watch list from buying firearms.
Trump has so far backed legislation introduced by Sen. Bill Nelson, D-Florida, to require that FBI investigators be notified whenever anyone ever investigated for terrorism buys a gun.
"We're not saying: don't sell guns to someone just because they were investigated," Nelson said in a statement. "But having a system in place that alerts the FBI if someone they once investigated is suddenly trying to purchase multiple assault weapons is just common sense."