Earlier this month, Hillary Clinton and Bernie Sanders battled—first in a Twitter flame war, then a Democratic town hall, and finally during a primary debate on MSNBC—over the definition of progressivism and who deserves to assume the mantle. Sanders pointed to the Wall Street cash pouring into Clinton’s campaign, and she countered with a familiar trump card: The Vermont senator’s long voting record in favor of gun owners. Clinton rightly recognizes that it’s the one issue where she can convincingly outflank Sanders on the left. As she put it in the MSNBC debate, “I don’t think it was progressive to vote to give gun makers and sellers immunity.”

Gun control has become a key issue within the Democratic Party, with President Barack Obama recently taking executive action intended to expand background checks of potential buyers, including those at gun shows and online. Polls consistently show that most Democrats, and even half of independents, favor stricter gun laws.

And yet, Clinton’s attacks don’t seem to be working: Sanders continues to close the gap in national polls. Do his famed Millennial supporters even care about his record on guns?

“Oh yeah, it’s just not much of an issue for me,” said Arona Kessler, 29, a professional pro-choice advocate from Alexandria, Virginia. “I am willing to say Sanders has been a little hypocritical when it comes to guns, but it is not enough to make my support waver,” she added. “And I do support stronger gun control.”

So does Jason Mazza, a 21-year-old college student on Long Island. “I think we need to be more careful who we are allowing to have guns,” he explained. “Overall though, gun control isn’t really that important of an issue to me.”

Michael Heinz, 27, who works for a camera company in Brooklyn, even insists that Sanders will have a greater impact on gun control than Clinton because of his campaign finance reform plan—the theory being that politicians won’t have to fear the National Rifle Association, and thus will back reasonable gun control measures.

“[T]he NRA’s money being the lifeblood for so many in Congress is what’s preventing us from joining the civilized world in this issue,” he said. The power of true campaign finance reform can’t be understated, and it’s what is in the way of real progress on the gun issue.”

These sentiments must be disheartening to the gun control groups that have injected themselves into the primaries, largely breaking in favor of Clinton.

“Where Clinton has come out in front on the gun violence issue, making it a key piece of her campaign, Senator Sanders has only discussed it when asked,” said Dan Gross, president of the Brady Campaign to Prevent Gun Violence, which has endorsed Clinton. “Hillary Clinton has led on this issue and that’s going to be an essential factor for voters as the primaries continue.”

It’s unclear whether it will be a factor, “essential” or otherwise. A December poll from the New York Times and CBS News found that guns were the fourth most important problem facing the country—but the poll was conducted days after the San Bernardino shooting. More recent polling suggest that the issue won’t motivate voters: A Gallup poll released this month found that “gun policy” was “below average in importance to both parties.”

Everytown for Gun Safety, an umbrella organization of advocacy groups that focus exclusively on curbing gun violence, insists that there’s been progress on the issue. “If you look at the big picture, in recent presidential election history, I think gun policy has sort of catapulted into one of the issues that voters have in mind,” said spokesman Erika Soto Lamb. “Democratic nominees fighting each other over who is better on gun policy represents a profound shift on the issue.”

In 2014, Everytown targeted key races across the country, investing money and cutting ads for candidates who supported stronger gun safety measures. They launched a campaign asking people to pledge to be gun sense voters, and more than a million signed up. But if the goal was to create more single-issue voters who will back the strongest candidate on guns, 2016 has so far failed to produce any evidence that any significant number of these voters exist. Consider the Iowa caucuses: Voters favored Clinton’s stance on gun control by a 9-point margin, but she barely won.

Meanwhile, Sanders has shifted left on guns in recent weeks, weakening Clinton’s advantage on the issue. After months of defending his 2005 vote for the Protection of Lawful Commerce in Arms Act, which shielded gun manufacturers from any litigation brought by victims of gun violence, he promised to work to repeal the law. Sanders has also reiterated his support for expanded background checks and an assault weapons ban.

“Voters have pushed the candidates to be on the same page on gun policy, and it just shows the power of the movement that didn’t exist before,” said Lamb. “They were not being asked questions on this issue and now they are.”

Unlike the Brady Campaign and Americans for Responsible Solutions—Gabby Giffords’s group, which also backs Clinton—Everytown has yet to endorse a candidate. Lamb says the group might still do so. Perhaps Everytown is waiting to see whether Michael Bloomberg, one of its largest single benefactors and the founder of Everytown subsidiary Mayors Against Illegal Guns, will indeed make an independent bid for the White House.