PHOTO: AFP/Getty Images
Now playing
02:19
Bernie Sanders, Hillary Clinton nearly even in Nevada
bernie sanders still feels the bern origwx allee_00011828.jpg
bernie sanders still feels the bern origwx allee_00011828.jpg
Now playing
01:56
Bernie Sanders still feels the bern
bernie sanders democrats trump bannon bts_00000924.jpg
bernie sanders democrats trump bannon bts_00000924.jpg
Now playing
01:18
Sanders: Democrats will work with Trump if ...
Republican presidential candidate Donald Trump addresses a rally against the Iran nuclear deal on the West Lawn of the U.S. Capitol September 9, 2015 in Washington, D.C.
PHOTO: Chip Somodevilla/Getty Images North America/Getty Images
Republican presidential candidate Donald Trump addresses a rally against the Iran nuclear deal on the West Lawn of the U.S. Capitol September 9, 2015 in Washington, D.C.
Now playing
02:40
Can Trump be trusted with nuclear weapons?
SANTA MONICA, CA - JUNE 07:  Democratic presidential candidate Senator Bernie Sanders (D-VT) greets supporters at an election-night rally on June 7, 2016 in Santa Monica, ia. Hillary Clinton held an early lead in today
PHOTO: Scott Olson/Getty Images
SANTA MONICA, CA - JUNE 07: Democratic presidential candidate Senator Bernie Sanders (D-VT) greets supporters at an election-night rally on June 7, 2016 in Santa Monica, ia. Hillary Clinton held an early lead in today's California primary. (Photo by Scott Olson/Getty Images)
Now playing
02:20
Five moments from Bernie Sanders' improbable run
security scan
PHOTO: DHS
security scan
Now playing
03:04
Fear, anger over potential 'Muslim registry'
PHOTO: CNN
Now playing
02:05
Bernie Sanders says he will work with Donald Trump
Student slams Clinton
PHOTO: Youtube/David K
Student slams Clinton
Now playing
01:15
Student bashes Clinton ... at Clinton event
dnc convention roll call brother larry sanders sot _00012118.jpg
dnc convention roll call brother larry sanders sot _00012118.jpg
Now playing
01:23
Bernie Sanders gets emotional at DNC roll call
Sen. Bernie Sanders speaks to reporters in Oakland, California. May 30, 2016.
PHOTO: CNN
Sen. Bernie Sanders speaks to reporters in Oakland, California. May 30, 2016.
Now playing
01:36
Secret Service rush stage at Bernie Sanders rally
Bernie Sanders takes the stage at the DNC Convention
PHOTO: CNN
Bernie Sanders takes the stage at the DNC Convention
Now playing
01:00
Bernie Sanders takes the DNC stage, crowd goes crazy
Bernie Sanders speaks to members of the press before being introduced at the Allen Temple Baptist Church in Oakland, California on May 30, 2016.
PHOTO: JOSH EDELSON/AFP/Getty Images
Bernie Sanders speaks to members of the press before being introduced at the Allen Temple Baptist Church in Oakland, California on May 30, 2016.
Now playing
02:56
It's 'Bernie or bust' for some Sanders supporters
U.S. Sen. Bernie Sanders (I-VT) speaks during a campaign rally with democratic presidential nominee former Secretary of State Hillary Clinton at University of New Hampshire on September 28, 2016 in Durham, New Hampshire.
PHOTO: Justin Sullivan/Getty Images
U.S. Sen. Bernie Sanders (I-VT) speaks during a campaign rally with democratic presidential nominee former Secretary of State Hillary Clinton at University of New Hampshire on September 28, 2016 in Durham, New Hampshire.
Now playing
02:51
Sanders walks fine line on Clinton hacked audio tape
Bernie sot 3
PHOTO: CNN
Bernie sot 3
Now playing
02:23
Sanders' new message to his supporters
PHOTO: Getty Images
Now playing
03:20
Who voted for Sanders and can Trump win them over?
FAIRFIELD, CA - JUNE 03: Democratic presidential candidate, U.S. Sen. Bernie Sanders (D-VT) speaks during a campaign rally at Cloverdale Municipal Airport on June 3, 2016 in Cloverdale, California. Five States including California will hold the final Super Tuesday primaries next week. (Photo by Ramin Talaie/Getty Images)
PHOTO: Ramin Talaie/Getty Images
FAIRFIELD, CA - JUNE 03: Democratic presidential candidate, U.S. Sen. Bernie Sanders (D-VT) speaks during a campaign rally at Cloverdale Municipal Airport on June 3, 2016 in Cloverdale, California. Five States including California will hold the final Super Tuesday primaries next week. (Photo by Ramin Talaie/Getty Images)
Now playing
02:07
What the end of the Sanders primary campaign looks like

Story highlights

Bernie Sanders said his campaign was assembling a "comprehensive package" of plans to address gun violence in the United States, but the plan has not been introduced

Gun control has been a nagging issue for Sanders since he launched his campaign last year

Hillary Clinton has successfully used the issue as a wedge to hurt Sanders' liberal bona fides

(CNN) —  

In response to a series of mass shootings last year, Bernie Sanders said that his campaign was assembling a “comprehensive package” of plans to address gun violence in the United States.

Months later, the insurgent candidate has failed to live up to that pledge.

Sanders’ campaign has yet to issue a detailed policy paper on gun control, something the candidate has done for a slew of other economic and core-Democratic issues. And his campaign does not list fighting gun violence on his more than 20-position-long issue page on his website.

Sanders’ aides did not respond to multiple requests about why his campaign has not announced a “comprehensive” gun plan as promised.

Gun control has been a nagging issue for Sanders since he launched his campaign last year. While Sanders has appealed to the left of the party on campaign finance, education and health care, guns are one issue that Hillary Clinton has successfully used to hurt Sanders’ liberal bona fides. That matters in a state like South Carolina, where the Vermont senator still needs to grow his base of support.

Clinton’s campaign has hammered Sanders on gun control, telling voters that while the Vermont senator talks about standing up to powerful interests, he has failed to do that with the National Rifle Association and the gun lobby.

Most notably, Sanders voted against barring the Centers for Disease Control and Prevention from studying gun violence in 1996 and voted against versions of the Brady Handgun Violence Prevention Act five times from 1991 to 1993.

Sanders has called the Clinton attacks on guns “very disingenuous.”

“I have a D-minus voting record from the NRA,” Sanders said during a January debate in South Carolina. “I support what President Obama is doing in terms of trying to close the gun show loopholes.”

Clinton has focused on the issue for much of her campaign, pledging to close a series of gun control loopholes and revoke licenses from bad actor gun sellers.

Sanders’ most comprehensive statement on guns came shortly before the January debate, when the senator reversed his position on a 2005 Senate vote that gave gun manufacturers immunity from prosecution. As a member of the House of Representatives at the time, Sanders voted in favor of that bill.

“I’m pleased that this legislation is being introduced,” Sanders said of Sen. Richard Blumenthal and Rep. Adam Schiff’s proposal to take away immunity from gun manufacturers when their products are used in crimes. “As I have said for many months now, we need to look at the underlying law and tighten it up.”

Sanders has declined to call the 2005 vote a mistake a number of times, citing the fact that he worries about the impact rescinding immunity would have on small, family-owned gun shops.

In supporting the legislation, Sanders also said he would propose an amendment to the bill that “would require the Commerce Department to monitor and report on the law’s impact in rural areas on the availability of hunting supplies, including firearms, sold by non-negligent local gun stores.”

In the face of public pressure after mass shootings, Sanders said last year that “the status quo clearly is not working and people on both sides of this issue cannot simply continue shouting at each other.”

But the Vermont senator has tempered his usual fire and bluntness when it comes to guns, stressing a more cautious approach to addressing mass shootings.

“If somebody has a gun and it falls into the hands of a murderer and that murderer kills somebody with the gun, do you hold the gun manufacturer responsible?” he asked at the Democratic debate in Las Vegas in October. “Not any more than you would hold a hammer company responsible if somebody beats somebody over the head with a hammer. That is not what a lawsuit should be about.”