In the days after the San Bernardino, Calif., shooting, the national debate quickly zeroed in on threats posed by those who wish to do Americans harm.

GOP presidential candidates -- and most notably front-runner Donald Trump -- helped frame it in no uncertain terms. President Obama isn't stopping terrorists from infiltrating our country, they said, so maybe we should ban Syrian refugees from immigrating into the country for now -- or even all Muslims, as Trump eventually proposed.

Through it all, gun-control proponents have struggled to find a way into the conversation -- to do something, anything, to move their cause forward after the deadliest mass shooting since Newtown, Conn. It helps explain why the New York Times felt moved to put it's Dec. 5 editorial calling for new gun laws on the front page -- the first time it had done so in 95 years.

And now, it helps explain why banning guns for those on the no-fly list -- an inarguably imperfect and relatively small-ball approach -- is nonetheless becoming gun-control supporters' biggest, best rallying cry.

President Obama, who struggled to be heard after San Bernardino and Paris conversation and decided to deliver a rare Oval Office address Sunday night, made sure to mention the no-fly list in his short speech. "What could possibly be the argument for allowing a terrorist suspect to buy a semiautomatic weapon?" he asked. "This is a matter of national security."

Congress had already voted down that idea a week earlier. But on Thursday, that small ball was moved forward in two small ways.

First, Connecticut Gov. Dannel Malloy (D), an outspoken gun-control advocate, announced that if state officials can get access to the list, he'll issue an executive order banning anyone on it from buying a gun in his state.

Then, House Minority Leader Nancy Pelosi (D-Calif.) tried to essentially take over the House floor to bring the no-fly ban up for a vote. She's pulling her leadership card in a parliamentary move called a privileged position to try to force Republicans to bring it up for a vote, reports Matt Fuller of the Huffington Post. Doing so would put Speaker Paul D. Ryan (R-Wis.) and his party in the somewhat politically awkward position of blocking the vote. (Ryan, who traditionally has the power to decide what comes up for a vote and what doesn't, has already called the proposal "a distraction.")

Congressional Democrats are clearly trying to make a political point here; Fuller also reports Democrats' campaign committee started running radio ads Thursday against vulnerable Republicans, accusing them of opposing the idea.

Pelosi and Malloy -- who notably was just elected to head the national Democratic Governors Association -- are gambling that the American people will side with them if they pitch the ban in as black-and-white terms as possible. They argue it's a common-sense solution, much like expanding background checks for all gun sales. Of course, while polls showed as many as 90 percent of Americans consistently supported that idea, it still didn't pass in Congress in 2013 after most Republicans balked.

So why might this proposal succeed where that one didn't? The idea is that this will be hard to vote against since it pertains to terrorists potentially obtaining guns. It's not a gun issues, per se, as much as a guns and terrorism issue.

"If you cannot fly due to being on a government watch list, you should not be able to buy a firearm," Malloy said.

But it's still a tough sell for a law that would deal with only a sliver of gun violence in then nation.

Trying to close this supposed "loophole" isn't a new approach. The George W. Bush administration originally drafted legislation to do this back in 2007, and it's been introduced in every Congress since, according to a fact sheet from the liberal think tank, Center for American Progress.

Gun-control supporters argue it's increasingly necessary due to a rise in terrorist-tied domestic shootings. The July shooting at a military recruiting center in Tennessee, the attempted May shooting at an anti-Muslim art show in Texas, the 2009 shooting at a Texas military base, San Bernardino -- all had links to extremism, they point out.

"When you start looking at 'what are some of the loopholes in our laws that will make it easier for the threat of active shooter terrorism to become actualized in the U.S.,'" said Mark Prentice, communications director for the gun-control group Americans for Responsible Solutions, "you very quickly go to this gap in law."

But until recently, the law hasn't been a top priority. That's in large part because instituting the ban wouldn't change the fact that other gun-control goals -- like expanding background checks, making it easier to track guns purchased and putting more restrictions on private sales  -- would still be unanswered.

It also isn't a panacea for the problem of bad guys getting guns. CNN reported the two San Bernardino attackers notably weren't even on a terrorist watch list.

And the list itself is controversial, shrouded in secrecy about who's on it and how they got there. Civil liberties groups and the pro-gun lobby repeatedly point out that the late Sen. Ted Kennedy (D-Mass.) was once on the list.

Making things more difficult for gun-control advocates is that the no-fly gun ban debate doesn't fall along traditional partisan lines -- as the NRA/civil liberties alliance suggests. Sen. Dianne Feinstein (D-Calif.) proposed the ban that recently failed in the Senate, while the Los Angeles Times editorial board rebutted the idea.

"[P]eople on the no-fly list (as well as the broader terror watch list from which it is drawn) have not been convicted of doing anything wrong," the paper's editorial board wrote.

More moderate GOP presidential candidates, like New Jersey Gov. Chris Christie and Ohio Gov. John Kasich, say they'd be open to the idea of banning people on terrorist watch lists -- whether the no-fly list or another -- from getting guns. So would Sen. Kelly Ayotte (R-N.H.), who is facing a tough reelection race. (Ayotte appeared to be signaling support here for a more conservative version of what Feinstein proposed.)

This June, the American Civil Liberties Union succeeded in getting the government to make it easier for people on the list to challenge their standing (though its lawyers recently argued the government hasn't done enough to that end.)

Finally, there are still unanswered questions about whether Malloy or any other governor can actually legally institute a ban. So even what he's doing risks being little more than a symbolic and futile effort.

Clearly the no-fly list isn't a perfect vehicle for gun-control opponents. It's messy, more controversial and more complicated than other widely supported proposals to limit access to guns. And it promises to be a big fight for only a small step in the direction of putting restrictions on guns and to limit gun violence.

But as its prominence after San Bernardino suggests, gun-control supporters seem to think its their best -- and perhaps only -- option to get some traction right now. And after years of frustration at the federal level, perhaps this is what they've been left with.