Bernie Sanders faced consistent criticism from the left on one issue in the 2016 Democratic primary: guns.

Opponents Hillary Clinton and Martin O’Malley attacked Sanders’s past votes against a bill in 1993 that established national background checks and for a bill in 2003 and 2005 that protects gun companies from lawsuits if their products are used in crimes. Sanders, an independent from rural and gun-friendly Vermont, defended the virtues of moderation on this issue — arguing, “We need a sensible debate about gun control which overcomes the cultural divide that exists in this country, and I think I can play an important role in this.”

But since 2016, Sanders, who’s now running for the presidential nomination in 2020, has taken a different tack on guns. He’s reiterated the need to expand background checks and ban assault weapons. He’s pointed to his broader support for gun control, and co-sponsored several Senate gun violence bills. In public appearances and social media, he’s highlighted his own past remarks, going back to the late 1980s, in which he called for a ban on assault weapons.

Guns were a rare vulnerability on the left for Sanders in the 2016 campaign — a weakness Sanders is now trying to avoid. But his shift also reflects a Democratic Party newly invigorated on gun control, as activists and survivors of the Parkland, Florida, school shooting have put the issue front and center. (To this point: One of Democrats’ first major votes after taking control of the House after the 2018 midterm elections was to pass a universal background check bill.)

Sanders emphasized the issue in his campaign announcement speech: “I’m running for president because we must end the epidemic of gun violence in this country. We need to take on the NRA, expand background checks, end the gun show loophole, and ban the sale and distribution of assault weapons.” (When I asked his campaign for comment for this article, a spokesperson pointed me to this part of the speech.)

Peter Ambler, the executive director of the gun control advocacy group Giffords, said that his organization endorsed Clinton in 2016 because “Bernie had a more troubling record.” But this time around, he said, things have changed.

The politics “have changed in a diametric way,” Ambler told me, pointing out that a lot of federal lawmakers have changed their positions on guns over the decades. “Bernie has evolved.”

Several likely and announced candidates, including Joe Biden, Cory Booker, and Kamala Harris, have long, consistent histories of supporting gun control. In what looks to be a crowded field of Democratic candidates, it’s not yet clear how Sanders’s past record — or his more recent evolution — will affect the race. But his shift on this issue helps show not just how he may have changed, but how the Democratic Party has changed as it becomes more vocal about gun violence in America.

Sanders’s record on guns is mixed

A fight about gun control is at the heart of how Sanders got into Congress in the first place. In 1988, when Sanders was mayor of Burlington, he first ran for the House. During that campaign, he supported an assault weapons ban and lost. In his telling, his support for that gun control measure might explain why he lost: Vermont is typically seen as liberal, but it’s also rural, and people tend to hold fairly conservative views on guns.

This eventually played in Sanders’s favor. The Republican who won Vermont’s US House seat, Peter Plympton Smith, went on to vote for an assault weapons ban — and the National Rifle Association aggressively opposed him when he was up for reelection. Although the NRA didn’t directly campaign for Sanders, he likely benefited from the campaign against his opponent when he went on to win his House bid in 1990.

For the next few years, Sanders treaded somewhat carefully on guns. That’s reflected by his NRA score over the past three decades, which has reached as high as a C-minus — not pro-gun, but more pro-gun than would be expected of a progressive.

In 1993, Sanders fulfilled a campaign promise and voted against the Brady Handgun Violence Prevention Act, which effectively set up background checks at the federal level. He said he opposed the measure because it imposed a five-day waiting period for background checks — at least until the federal government, years later, could develop an instant background check system that can take up to three days if the initial check is inconclusive.

This vote has plagued Sanders among gun control advocates for decades. Background checks are the foundation of national gun policy and politics, which to this day continue to focus in large part on expanding background checks. Yet Sanders voted against the bill that established this system.

Then in 2003 and 2005, Sanders voted for a bill that effectively shields gun companies from lawsuits. These votes became particularly contentious in 2016, because Hillary Clinton voted against the bill when she was in the Senate and cited her vote to draw a contrast to Sanders during the 2016 primaries. The bill became law in 2005.

Gun control advocates strongly oppose the law, arguing that it’s stopped victims in several cases from holding gun makers and dealers accountable for producing and selling firearms they should have known would be diverted to criminal uses.

Sanders also long spoke in fairly moderate terms about gun control. After the 2012 Sandy Hook Elementary School shooting, he largely supported the typical Democratic agenda on the issue — to expand background checks, reinstate the assault weapons ban (which Sanders voted for in 1994 when it became law, but which expired in 2004), and prohibit high-capacity ammo magazines, among other proposals.

But even then, he raised doubts about the measures’ effectiveness: He told Vermont’s Seven Days in 2013, “If you passed the strongest gun control legislation tomorrow, I don’t think it will have a profound effect on the tragedies we have seen.”

Extending to his presidential bid in 2015 and 2016, Sanders kept his moderate message on guns. He defended his record in an interview with CNN host Jake Tapper — arguing that he was trying to bridge a cultural divide on guns:

The people in my state understand — I think pretty clearly — that guns in Vermont are not the same thing as guns in Chicago or guns in Los Angeles. In our state, guns are used for hunting. In Chicago, they’re used by kids in gangs killing other kids, or people shooting at police officers [or] shooting down innocent people. We need a sensible debate about gun control which overcomes the cultural divide that exists in this country, and I think I can play an important role in this.

As the criticisms continued to stack up, though, Sanders’s tune began to change. In early 2016, he said he would sponsor a bill repealing the law that protects gun companies from lawsuits.

In the years since, Sanders’s shift — in rhetoric, if not policy — has continued.

Sanders has shifted in recent years

Sanders’s position on guns during the 2016 primary was one of his few vulnerabilities from the left. About 87 percent of Democrats in 2018 said gun laws in the US should be stricter, according to Gallup’s surveys.

So Sanders began to take more aggressive actions in favor of gun control. He’s co-sponsored bills to expand background checks, ban assault weapons, further prohibit domestic abusers from getting firearms, encourage the passage of “red flag” laws, restrict 3D-printed guns, and more.

His presidential campaign has also emphasized the issue. Just two days after he announced his campaign, his campaign posted a video on Twitter that highlighted his support for an assault weapons ban — going back to 1988 — and criticizing the NRA.

Gun violence is an epidemic in this country that must end. Our job: take on the NRA, expand background checks, end the gun show loophole and ban the sale and distribution of assault weapons. pic.twitter.com/Fv9IaqYKTD — Bernie Sanders (@BernieSanders) February 21, 2019

Gun control advocates argue that Sanders likely wants to avoid repeating the situation he saw in 2016.

“It’s pretty indisputable that there was a political cost in the 2016 primaries for Bernie for his contrast on guns,” Ambler of Giffords said. “In the years since, he’s worked with us on a few things.”

The question is whether Sanders has done enough. Guns are now an issue that has broadly animated Democrats, and the Democratic presidential candidates who have announced so far have by and large taken similar positions in favor of gun control. (Ambler said one of the challenges for his group is “the candidates have so little contrasts on the issue that it’s going to dampen the attention that the candidates themselves pay to the issue and dampen the news media coverage of the issue.”)

The broad similarities between candidates may keep Sanders vulnerable on this issue: If he and other candidates have the same policy positions, but he has a less consistent record on guns, then primary opponents could point to that record to differentiate themselves — just like Clinton did in 2016.

It’s also unclear just how far Sanders’s recent shift on guns will go. The research shows the most widely touted gun control measures — universal background checks and an assault weapons ban — may not do much to reduce gun violence on their own, even if they’re a necessary foundation for broader efforts. That’s why some researchers and activists have pushed for Democrats to go further on guns and support, for example, a licensing scheme for gun ownership and policies that can reduce the number of firearms in the US.

Sanders’s “political brand is wrapped up in this idea that he has big, bold visionary solutions for the future of our country, and he’s going to talk about them and build support for them. And it’s obviously part of the reason why the country’s now talking single-payer and a Green New Deal and a tax on megamillionaires and all that stuff,” Igor Volsky, director of Guns Down America, told me. “I would challenge Bernie to adopt a similar big vision on reducing gun violence and really building a future with fewer guns.”

When I asked if Sanders was willing to go further on guns, a spokesperson simply reiterated his support for “ending the epidemic of gun violence.”

But if activists push Democrats further to the left on this issue, Sanders may be left behind if he tries to maintain at least some of his moderate roots, or be forced to distance himself from his moderate past even more than he already has.

“The best way to show that you’ve overcome past challenges in your voting record is to do what I’m suggesting — to embrace a bolder approach to this issue than your competitors,” Volsky said.

Gun politics are changing in America

For Sanders, his record may be a growing challenge because gun politics also seem to be going through a significant change in America. After the Parkland school shooting in 2018, young activists inspired new passion in the issue — culminating in the March for Our Lives a month after the shooting.

Public opinion seems to have shifted as well, particularly among Democrats. When Gallup polled Americans about gun laws in 2014, 71 percent of Democrats said they wanted stricter laws. In 2018, that jumped 16 points to 87 percent. Overall, support for stricter gun laws climbed 14 points — to 61 percent — from 2014 to 2018.

If anything, Gallup’s findings understate levels of support for gun control: When people are asked about specific policies, support climbs to the 70s and 80s.

The problem, though, has never been whether a majority of Americans support gun control. The problem is what’s known as the intensity gap: Essentially, even though more Americans support gun control laws, those on the side opposing stricter measures have long been more passionate about the issue — more likely to make guns the one issue they vote on, more likely to call their representatives in Congress, and so on.

As Republican strategist Grover Norquist said in 2000, “The question is intensity versus preference. You can always get a certain percentage to say they are in favor of some gun controls. But are they going to vote on their ‘control’ position?” Probably not, he suggested, “but for that 4-5 percent who care about guns, they will vote on this.”

For Democratic lawmakers, this intensity gap made guns a touchy issue — with many blaming brutal 1994 electoral losses on their votes for an assault weapons ban that year.

This is where Parkland in particular seems to have had an effect, inspiring a new wave of activism that put the issue at the front for the public and made it more salient for newly elected Democrats. That’s why Democrats, upon taking the House, quickly prioritized a universal background check bill.

This was reflected in the 2018 midterm elections, where gun control advocates from both parties swept elections. Perhaps most relevant to Sanders, Vermont’s Republican governor, Phil Scott, signed gun control laws in the aftermath of Parkland that included expanded background checks and a “red flag” law. Scott, despite Vermont’s past reputation against gun control, handily won reelection — a sign that perhaps this issue isn’t the poison pill that politicians, including Sanders, have long feared.

The national shift helps explain why Sanders has moved to aggressively message his pro–gun control positions as of late. But it also makes him vulnerable, because his record over the decades could seem out of line with where the Democratic Party has moved.