WASHINGTON — The bloody attack in San Bernardino, Calif., last week revived fears about threats from groups such as the Islamic State in America and also fused two fraught policy debates central to the presidential contest: gun control and how far to go in the fight against terrorism.
“What could possibly be the argument for allowing a terrorist suspect to buy a semiautomatic weapon?” Mr. Obama asked in a prime-time address to the nation. “This is a matter of national security.”
The proposal, which has divided lawmakers along party lines, failed in the Senate last week, with just one Democrat and one Republican persuaded to switch sides on the issue. The four senators who are running for president — Marco Rubio, Rand Paul, Lindsey Graham and Ted Cruz — all voted against the measure.
Mr. Rubio, of Florida, cast the idea as another example of Democrats’ having too much faith in government, posing a threat to due process and potentially violating the rights of law-abiding citizens.
“The majority of people on the no-fly list are oftentimes people that basically just have the same name as somebody else, who don’t belong on the no-fly list,” Mr. Rubio said on CNN on Sunday, estimating that the majority of the more than 700,000 people on the list did not belong on it. “These are everyday Americans that have nothing to do with terrorism.”
Jeb Bush, the former governor of Florida, agreed with Mr. Rubio. He noted that Senator Ted Kennedy had been stopped from flying on multiple occasions because of problems with such lists and suggested that relying on a no-fly list would do more to slow innocent passengers than it would to stop would-be terrorists.
“This is not a list that you can be certain of,” Mr. Bush told ABC. “The first impulse of Hillary Clinton and Barack Obama is to have gun control.”
Proposals to impose any restrictions on guns have been a nonstarter in Congress in recent years, despite the increasing prevalence of mass shootings. Opponents of gun control argue that gun laws will not deter people intent on committing murder, and they assert that it is safer to be armed in a dangerous world.
But not all of the Republicans seeking the White House were so certain that gun rights should apply to people who the government thinks could be plotting terrorist attacks. For candidates who have claimed that they would be the toughest against terrorists, the idea of letting homegrown radicals easily buy guns was a concern.
Taking it a step further, Gov. John R. Kasich of Ohio characterized imposing gun restrictions on people on the no-fly list as an obvious measure. “Of course, it makes common sense to say that, if you’re on a terrorist watch list, you shouldn’t be able to go out and get a gun,” Mr. Kasich said over the weekend.
“I would certainly take a look at it,” Mr. Trump told CBS on Sunday. “I’m very strongly into the whole thing with Second Amendment. But if you can’t fly, and if you have got some really bad — I would certainly look at that very hard.”
The quality of the no-fly list and the criteria for being placed on it have been subject to debate over the years as high-profile passengers and regular travelers alike have been erroneously stopped in airports.
Being removed from such lists can be a challenge. Elizabeth Pipkin, a trial lawyer in California, spent nine years in litigation to get a client, Rahinah Ibrahim, removed from the list after she was stopped from flying in 2005 at San Francisco’s airport. Ms. Ibrahim, a Malaysian citizen and Muslim who was studying at Stanford University at the time, finally had her name cleared last year.
“There is really no criteria for these lists,” Ms. Pipkin said, arguing that using them to restrict gun purchases should worry anyone who is concerned about the Second Amendment. “The government can put anyone on it for any reason. It’s not the cure-all that some might think it is.”
But studies have shown that terrorism suspects do readily have access to guns. A report to Congress from the Government Accountability Office this year found that from 2004 to 2014, more than 2,000 people on the terrorist watch list were able to buy guns from dealers in the United States. Just 190 attempted transactions were denied.
The Department of Homeland Security did not immediately comment on the list, but a former senior counterterrorism official, speaking on the condition of anonymity because he was not authorized to discuss the matter, pointed out that the no-fly list is a small subset of the overall watch list of more than a million people, and that it is carefully vetted.
“The silliness of objecting to restricting gun purchases by people on the no-fly is exceeded only by how limited that step would be,” the former official said.