Had Hillary Clinton been looking for an easy hit, she could have hammered Donald Trump for his alleged mafia ties, his business failures, or his sordid personal history. She could have trotted out scammed Trump University students and wounded investors. But of all the rich material Clinton has at her disposal, she has been attacking Trump on something much less obvious: outsourcing.

On Wednesday, the Clinton campaign released its second Trump-the-outsourcer ad in the last month. “Shirts” features Robert Kidder, the owner of New England Shirt Company, who tells us his Fall River, Massachusetts, factory has been in business since 1883. “Trump’s products have been made in 12 other countries because he says there’s no place in America that can make them. Well, there is,” Kidder says, as images of the factory and its workers flash by. “Donald Trump says he’ll make America great again, while he’s taking the shirts right off our backs.”

Clearly, Clinton learned something from the failures of Trump’s foes in the GOP primaries. Their ad strategy, such as it was, involved throwing the kitchen sink at Trump, and they failed to make a dent. For now, at least, the Clinton campaign has chosen a central line of attack for its commercials and stuck to it. Earlier this month, during the Olympics, Clinton flooded the airwaves with “Some Place,” her first ad about outsourcing. Now she’s running “Shirts” on broadcast TV in seven key swing states.

The consistent focus makes sense. But why is outsourcing the theme? The obvious explanation for these ads is that Clinton is weak with white working-class voters—most worryingly in the key Rust Belt swing states of Ohio and Pennsylvania. (According to a recent Monmouth poll, for instance, Clinton is up narrowly in Ohio. But Trump has an 8-point edge among white voters in the state and a 24-point lead among white men.) While most campaign ads are designed to reinforce preexisting notions about the candidates, these outsourcing spots are more aggressive, designed to persuade them that Trump’s self-created image is outrageously false.

“Some people might say that Donald Trump is looking out for the average guy,” says Travis Ridout, a political science professor who studies campaign advertising at Washington State University. “These ads make you stop and think: Is that really the case?”

That’s the idea, anyway. In living rooms across the Rust Belt, people are learning that Trump has hopscotched across 12 countries in search of the cheapest places to manufacture his line of luxury dress shirts, suits, ties, and accessories. It’s a classic political maneuver: Hit your opponent where he’s perceived to be strong, and try to undermine his strengths.

But there’s a larger purpose to these ads—and a larger problem that is inspiring the Clinton campaign to run them. Trump represents a threat to the Democratic Party that goes beyond the slim chance he’ll carry Ohio and Pennsylvania and win in November. Trumpism is endangering the Democrats’ already shaky claim to stand for working people’s interests—not just in 2016, but over the long haul. With her outsourcing ads, Clinton isn’t just trying to win back some white-working class voters in Pennsylvania and Ohio. She’s trying to rescue the Democratic Party’s brand advantage.

In the past, Republicans have made it easy to paint them as enemies of American workers—never more so in 2012, when they nominated Mitt Romney. That summer, the Obama campaign hammered the message home with a series of ads claiming Romney had shipped jobs overseas. “Come and Go” focused on how he “shipped jobs to China and Mexico.” “Revealed” called outsourcing “Romney Economics.” A third ad from July, “Believe,” claimed Romney “supports tax breaks for companies that ship jobs overseas.” To reinforce this barrage on the airwaves, Obama took a “Betting on America” bus tour through Ohio and Western Pennsylvania.

The strategy helped Obama hold on to enough white working-class votes to carry Ohio and Pennsylvania. Romney did his part as well, of course, with his insistence that “corporations are people, my friend” and his damning remarks at a fundraiser about the “47 percent.” But none of it halted the long-term slippage of white-working class support for Democrats, which first became a problem during the Reagan era. Obama’s share of this vote declined nationally from his first campaign to his second, from 40 percent to 36 percent.

Effectively painting Romney as an outsourcer helped pump a little life into the old, somewhat faded party brands: The Democrats representing working folks, the Republicans standing for Wall Street financiers and the one percent. But Trump’s campaign has further upended those perceptions—among white Americans, anyway. His populist appeal has given him a massive lead among white working-class voters nationally: Around 58 percent of white voters without a college degree support him, while only 30 percent support Clinton.

That may not spell doom for Democrats in November, even if Clinton’s outsourcing attacks can’t move those numbers. But Trumpism will live on after the campaign even if Trump himself fades from the political scene—and threatens to alter Americans’ common, shorthand image of the GOP. The Republican nominee is the one going to West Virginia and donning a miner’s helmet, promising (magically) more coal jobs. He’s the one yelling the loudest for jobs to remain in the United States, for clothes to be made in the USA. (“Remember we used to have ‘Made in the USA’?” he asked voters in North Carolina, which has had huge losses in manufacturing jobs in recent decades, in March. “You don’t see that anymore.”) He’s the one who, in the finale of his convention acceptance speech, told white working-class voters, “I am your voice.”

However ludicrous the notion of Trump as vox populi may be, it’s working, at least for some. To make matters worse for the Democrats, their nominee is the furthest thing from a populist. She’s a political insider, and a wealthy one to boot. After so many years in the limelight as the epitome of a political insider and establishmentarian, remaking Clinton’s image to be more “regular-white-guy friendly” would prove difficult, if not downright impossible. The only option is to undercut Trump’s claim to populism.

Fortunately, his mile-wide hypocrisy (good luck finding that “Made in the USA” label on Trump ties!) makes a fat target. And the Trump campaign is allowing the outsourcing attacks to sink in: For the last month, Clinton has been on the air all but unopposed, while Trump was busy bickering with the Khan family and shaking up his campaign leadership for the second time this summer. He released his first televised ad only this week, a spot about the two Americas—but not the kind John Edwards meant: one safe and secure under Trump, the other overrun by immigrants with criminal records. The ad does nothing to counter the claims that Trump has shipped jobs overseas, and it’s not even running in many markets—he has spent just $72,000 in Ohio and $78,000 in Pennsylvania. Meanwhile, as my colleague Jeet Heer pointed out this week, Clinton has spent $17 million in Ohio and $6 million in Pennsylvania.

The outsourcing attacks could conceivably help Clinton win in November—and win big, if they boost her in Ohio and Pennsylvania. But Clinton and the Democrats have something much bigger at stake. The party’s claim to be “of the people”—white people included—rests largely on the public’s perception of the other guys as enemies of the people. The effort to soften up Trump’s populist brand, to make him just one more big-money Republican out to screw the people, is not just about winning on November 8—it’s also about all the election days to come.