“What could possibly be the argument for allowing a terrorist suspect to buy a semi-automatic weapon?” asked President Barack Obama on Sunday night, lobbing a political grenade at his opponents during his Oval Office address on the San Bernardino shooting. As leading Republicans search for a viable answer to his question, the issue at its core may be opening a fissure in the party, which in recent years has strenuously resisted any new restrictions on gun ownership.

Obama’s query was the latest move by Democrats to press their political advantage on the so-called “terror gap,” which refers to the fact that persons on the consolidated terror watch list are not included in the background check system used to vet gun buyers. Republicans who object to legislation drafted by Democratic California Senator Dianne Feinstein and Republican New York Representative Peter King to plug the terror gap echo criticisms of the proposal surfaced by the National Rifle Association. They point out — correctly — that the watch list has at times included people who don’t belong on it, who would be incorrectly stripped of their gun rights should the legislation pass. “I’ve even had family members that have shown up on that list,” Ohio Representative Bill Johnson told MSNBC. “And I guarantee you, they’re not radicalized.” But that rationale has not provided conservatives with an escape from the bind that the issue puts them in.

“This is a lose-lose for Republicans,” says Robert Spitzer, a political scientist who’s written extensively about gun politics, tells The Trace. On the one hand, if they agree that people on the terror watch list shouldn’t have firearms, they risk being branded turncoats on gun rights. But if they fight against closing the terror gap, Spitzer adds, “you are pandering to terrorists and that is, to most people, the opposite of defending national security.”

Faced with that choice, GOP presidential hopeful Chris Christie on Monday became the most prominent Republican to break from the party line. In 2013, as New Jersey governor, he had signed legislation barring those on the terrorist watch list from purchasing guns in New Jersey. But during a late November interview with CNN’s Jake Tapper he tried to have it both ways, arguing implausibly that the issue should be left to the states — in essence saying that while New Jersey had decided to address the terror gap, if Pennsylvania wants to let possible jihadists go to their local gun store to stock up on AR-15s for a cross-country shooting spree, then that’s Pennsylvania’s business. Christie’s new position, relayed to the influential Weekly Standard, is that he does “not have a huge problem” with federal measures to bar persons with suspected terror ties from arming themselves with firearms. Another Republican running for president, Ohio Governor John Kasich, was more blunt: “If you’re on a terrorist watch list, you shouldn’t be able to go out and get a gun.”

Christie and Kasich are jousting with Jeb Bush and Marco Rubio in what might be called the electability primary, the race within the race that may determine who emerges as a leading alternative to Donald Trump. Rubio, for his part, has been wary of losing right-wing voters already put off by his past involvement in a bipartisan push for immigration reform, and a no-compromise position on gun rights is one way he’s tried to burnish his conservative bonafides. The reason he doesn’t support closing the terror gap, he explained on CNN on Monday, is that the government’s watch lists are too long, a product of their containing innocent names. “There are over 700,000 Americans on some watch list or another that would all be captured under this amendment the Democrats offered,” he said. “And that’s the problem.”

Rubio’s stat was “way off,” reported Politifact. While the overall list may be that big, the vast majority of the persons on it are foreigners — the number who are Americans is no more than 10,000. In addition to leaving Rubio vulnerable to charges that he’s more concerned with appeasing the gun lobby than protecting the homeland, his position on the terror gap has now led him to get caught in a significant exaggeration.

The other big political fight heading into 2016 is for control of the Senate, where Republicans’ initial response to the terror gap was embodied by Senator Mitch McConnell. Asked about the issue when it first reemerged in the wake of the Paris attack, he pled ignorance, saying he was “not particularly familiar” with the Feinstein bill, despite having attended at least three committee hearings where it was discussed, dating as far back as 2009.

When reports emerged that the San Bernardino shootings qualified as an act of terrorism, Democrats quickly maneuvered to force a vote on Feinstein’s proposed fix, which failed along party lines. No longer able to duck the issue, Republicans offered an alternative sponsored by Texas Senator John Cornyn — a tacit acknowledgement that the terror gap might represent a national security risk, and one also crafted to appease diehard pro-gun voters. Cornyn’s measure would give the U.S. Attorney General power to delay firearms purchases made by persons on the terror watch list for up to three days while the Department of Justice seeks a court order to prevent the sale.

Cornyn’s measure didn’t go anywhere, either, keeping alive Obama’s question — What could possibly be the argument for allowing a terrorist suspect to buy a semi-automatic weapon? — and keeping Republican Senators up for reelection in the hot seat. New Hampshire’s Kelly Ayotte, a freshman expecting a tough race in 2016, voted against closing the terror gap when the Feinstein proposal when it came up last Thursday, but backs Cornyn’s alternative. Through a spokesperson, Ayotte’s opponent, Governor Maggie Hassan, parried by telling a local NPR affiliate that she “supports restricting access to guns for those on the no-fly list — without any conditions.”

One Republican strategist is concerned about the pickle that the terror gap presents for his party. “It is very difficult to explain in a soundbite what’s wrong with ‘no-fly, no-buy’, even though there’s plenty wrong with it from a civil liberties perspective,” says an ex-aide to Senator and former presidential candidate John McCain, who asked not to be identified because he consults for several U.S. Senate campaigns. “Democrats have found a way to push gun control and be anti-terrorism at the same time, and we’re expecting this to be a very effective line of attack. They will be a dog with a bone on this one.”

On both Tuesday and Wednesday, House Democrats tried to use procedural measures to force a vote on a bill that would close the loophole. A similar effort had failed last week.

[Photo: Flickr user Gage Skidmore]