"The Bipartisan Safer Communities Act is a classic example of Washington dysfunction," he said in a June 23 press release explaining his vote in opposition. "Negotiated by a 'gang' with no committee process and no ability to offer amendments, billions in spending with a phantom pay for, and provisions that ignore constitutional rights."

Despite promising not to seek a third term in the Senate, Johnson is currently doing so anyway. Polls show Johnson faces an uphill battle, with among the lowest approval ratings of any incumbent senator in the country. The Democratic primary will be held Aug. 9 and will determine his general election opponent out of a field of eight candidates.

The issues pages on Johnson's Senate and campaign websites omit any mention of his positions on gun violence. His spokespersons did not respond to an inquiry for this story, but a review of his past comments and votes makes clear he has opposed virtually every proposed measure to curb gun violence.

Johnson has opposed multiple efforts to make sure that everyone goes through a background check before obtaining a firearm.

In a May 5 ABC News interview, he argued that there was no need to have universal background checks because some gun purchases already require them. "We have background checks. What we ought to do is enforce the laws that are on the books," he said, seemingly contradicting his own longstanding efforts to roll back existing state gun restrictions.

In September 2019, he told constituents that background checks could criminalize people who disobey them, and some people might ignore them. "My reluctance is: I don't want to turn into a criminal some guy up in northern Wisconsin who transfers a gun to a friend," Johnson said. "You can pass all the background checks. It's not going to solve this. It probably won't even stop one of these."

"It doesn't take a whole lot of imagination to realize if someone is going to break the law and slaughter a fellow human being, they're not going to have a whole lot of problem violating gun laws either. We have 400 million guns. People are going to be able to get them," he added.

He voted against a 2013 proposal by Sens. Joe Manchin (D-WV) and Pat Toomey (R-PA), which would have required a background check prior to any online or gun show firearms purchases, even though their compromise proposal explicitly exempted transfers between family and friends.

Johnson also voted in 2017 to block a federal rule to stop gun purchases by people adjudicated to be mentally unable to handle their own finances.

In August 2019, Johnson told the Milwaukee Journal Sentinel that legislation to stop sales of semi-automatic assault weapons was also unnecessary. After questioning whether semi-automatic rifles are even assault weapons, he said he was against banning them because "You can create a lot of carnage with not using a gun. People attack crowds with trucks." (Truck drivers typically are required to obtain a license.)

Johnson voted against proposals in 2013 to ban the sale of those assault weapons and high-capacity magazines.

During a 2012 interview, he told Fox News that he believes large ammunition-feeding devices are a constitutional right. According to a HuffPost report at the time, Johnson told the network, "People will talk about unusually lethal weapons, that could be potentially a discussion you could have. But the fact of the matter is there are 30-round magazines that are just common all over the place. You simply can't keep these weapons out of the hands of sick, demented individuals who want to do harm. And when you try and do it, you restrict our freedom."

In 1996, an amendment proposed by then-Rep. Jay Dickey (R-AR) was included in the appropriations bill for the following year that stipulated "none of the funds made available for injury prevention and control at the Centers for Disease Control and Prevention may be used to advocate or promote gun control." A 2012 appropriations law similarly prohibited the National Institutes of Health from researching ways to curb gun violence. In practice, this meant that for years the federal agencies were blocked from studying how to prevent the tens of thousands of gun deaths each year in the United States.

Dickey, who lost his seat in the 2000 election, told NPR in 2015 that he regretted that result of his amendment and that more research was needed.

But when Congress finally lifted the prohibition in December 2019, as part of a broader budget agreement, Johnson was one of just 23 senators to vote no on the bipartisan package. He complained in a press release that "the price for funding necessary programs was simply too high to obtain my overall support."

In April 2019, during a discussion with high school students in Columbus, Wisconsin, Johnson was asked why he did not support modernizing gun laws as other countries have successfully done to curb gun deaths.

"Australia and Japan took away gun rights and gun violence in those countries went way down," a student said.

Johnson responded, "Those are different cultures. I support our rights to have guns and defend ourselves."

During his 2010 and 2016 campaigns, the National Rifle Association endorsed Johnson and gave him its highest ratings. In the later race, the group praised his "proven record of support for our Second Amendment freedoms." Its endorsement release noted his agreement with the group on basically every issue: opposing "anti-gun Supreme Court justices" and "anti-gun bureaucrats," supporting "right-to-carry," and opposing background checks.

With its endorsement, the group also invested heavily in his campaigns. In addition to giving him at least $13,400 in political action committee contributions, the NRA spent more than $1 million in dark money to support him and attack his Democratic opponent.

The anti-gun violence group Giffords filed sued two NRA affiliates and a number of campaign committees in the U.S. District Court for the District of Columbia in November 2021, charging: "Over the past seven years, the National Rifle Association ("the NRA") has engaged in an ongoing scheme to evade campaign finance regulations by using a series of shell corporations to illegally but surreptitiously coordinate advertising with at least seven candidates for federal office." The suit is still working its way through the courts. An NRA spokesperson dismissed the suit, telling NPR it was a "misguided" attack and a "premeditated abuse of the public by our adversaries."