In the Democratic race for the presidential nomination, Hillary Clinton is facing a stronger-than-expected challenge from the left by Vermont Senator Bernie Sanders. Three recent polls show Sanders pulling ahead of Clinton in Iowa, with margins ranging from 1 to 8 percent. But when it comes to guns, Sanders is now following Clinton’s lead.

On Monday, Iowa voters began to receive a pamphlet touting Sanders’s record as a “lifelong advocate of gun safety.” The literature cites the Senator’s history of supporting “common sense gun safety laws” like assault weapon bans, limits on magazine capacity, closing the gun show loophole, and expanding the background check system. It promises he will pursue similar initiatives if elected. The mailer highlights Sanders’s “D-” rating from the National Rifle Association (NRA); the grade is splashed across a red band in the middle of the page, under a heading that asserts “we can trust Bernie to stand up to the NRA.”

For months, guns have been the one issue where Sanders’s aggressive underdog campaign has been on the defensive. Sanders is clearly feeling the heat from progressives that guns are an issue he has to take seriously,” Emily Tisch Sussman, a campaign director at the Center for American Progress, told The Trace. “He had previously defended his mixed record as a reasonable record representing his home state, but no longer thinks that plays sufficiently on a national stage.”

The Sanders campaign did not return a request for comment regarding which groups of voters it is targeting with the pamphlet. Direct-mail literature is often sent to highly-specific audiences that a campaign has identified using previous polling or demographic information. One Iowa Democrat, a 40-year-old white male, received the Sanders gun mailer and passed it on to Stephen Clermont, the director for research and policy at Every Child Matters, an education advocacy group. “My guess is that they have [identified] this voter as either a soft Sanders, a soft Clinton, or undecided, and their polling is telling them that guns is a key issue holding people back from supporting Bernie,” Clermont told The Trace.

The Sanders campaign has noticed that “the gun issue is resonating.”

“There are two types of political mailings: persuasion mail and mobilization mail,” said Sasha Issenberg, author of The Victory Lab: The Secret Art of Winning Campaigns. Campaigns send persuasion mail to either retain reliable voters’ support, or persuade voters who favor another candidate to jump ship. Mobilization mail aims to motivate people who definitely support the candidate to actually show up on caucus day. After reviewing an image of Sanders’ gun mailer, Issenberg told The Trace, “This looks like persuasion mail.”

Describing the likely recipients of the mailer, Issenberg added, “Either they’re Bernie supporters who might have misgivings on guns, or they’re Hillary supporters who Sanders might be able to win over on Wall Street issues, but need to reassure on gun issues.” Whatever the case, the Sanders campaign has noticed that “the gun issue is resonating,” Issenberg said. The cost and time involved in targeting voters, creating and approving the brochure, and actually getting it in the mail suggested to Issenberg that it was sent to at least 1,000 voters. That number is significant, “considering the size of the persuadable Iowa electorate,” he said.

Sanders’s campaign sent the mailer several days after two prominent gun violence prevention groups reproached Democracy for America, a grassroots liberal organization, for praising Sanders’s record on guns. The Brady Campaign to Prevent Gun Violence and Americans for Responsible Solutions, both of which have endorsed Hillary Clinton, sent a letter to Democracy for America stating that they were “taken aback” when the group said that Sanders has a “strong record against gun violence.” Many gun violence prevention advocates have disputed this talking point, citing Sanders’s votes against various incarnations of the Brady Bill, which created the federal background check system. Sanders also voted for the Protection of Lawful Commerce in Arms Act, or PLCAA, which prevents gun businesses from being held legally liable for gun-related violence.

The Brady Campaign was not impressed with Sanders’s mailer. Speaking with a Buzzfeed reporter, the organization’s president Dan Gross called Sanders’s claims “offensive.” He pointed to the Senator’s vote for PLCAA and called the law “one of the most evil pieces of special interest legislation ever passed.” Sanders has refused to reverse his position on PLCAA completely, but he has conceded that he would vote to “revise” the bill: Earlier this month, he said that while “a small gun shop in northern Vermont” should be protected when its products are misused, big gun companies should be scrutinized if their products are disproportionately used in crimes. It’s small gun shops, however, that are most directly responsible for distributing guns and letting them get into the hands dangerous persons.

[Photo: Flickr user Michael Vadon]