Republicans, already struggling to find an effective line of attack against Kamala Harris, seem even more knotted up by her running mate, Tim Walz.

The Minnesota governor, who made his debut with Harris at a spirited Tuesday evening rally in Philadelphia, came out swinging against Donald Trump and JD Vance—not only describing the pair as “creepy” and “weird as hell,” but as narcissistic frauds out of touch with the issues facing mainstream America. “Donald Trump is not fighting for you or your family,” Walz told the fired-up crowd. “And I got to tell you, his running mate shares his dangerous and backwards agenda for this country.”

Trump and his allies immediately tried to hit back, but have so far just punched air. Trump, who fantasized Tuesday about Joe Biden jumping back into the race, said in a Fox & Friends rant on Wednesday morning that Walz is “insulting to anything having to do with making America great again,” calling his opponents communists and describing the Minnesota governor as being “very heavy into transgender.” Vance, the target of a memorable “couch” joke by Walz, cast Harris’s Nebraska-born ticket mate as a “San Francisco-style liberal” whose career—as a National Guardsman, a teacher and coach, a congressman, and a two-term governor—has been a “joke.” And Trump adviser Stephen Miller, whose weirdness might exceed that of his boss, claimed Tuesday on Fox News that Harris and Walz would “turn the entire midwest into Mogadishu.”

“This man, they call him ‘Tampon Tim,’ is a full-blown radical left communist,” Miller added on Newsmax, referring to the law the governor signed requiring menstrual products to be provided in all school restrooms in the state. “Tim Walz’s job is to be the Jack Kevorkian for America. His job is to be the assisted suicide doctor, to lean over charmingly by the bedside of America and to give it a fatal injection.”

If all that seems like hyperbole, it may be because Republicans haven’t found anything more tangible to go after him with. Walz is, indeed, progressive, but the efforts to paint him as some kind of limousine liberal just don’t ring true—partly because of his record of bipartisanship, but also because he grounds his progressive policy positions in the bedrock American values Republicans try to lay claim to. “Some of us are old enough to remember when it was Republicans who were talking about freedom,” Walz said Tuesday. “It turns out now what they meant is the government should be free to invade your doctor’s office.”

“There is a golden rule,” he continued. “Mind your own damn business.”

That line could be a campaign slogan for Democrats—even more than the “Republicans are weird” one Walz popularized—as their opponents run a campaign fueled by resentment. Trump and Vance have styled themselves as the protectors of Real America. But they are merely playing dress-up as populists while Trump, as Walz put it Tuesday, sits around wondering “how he could cut taxes for his rich friends.”

He obviously isn’t the first Democrat to point that out. But Walz is a particularly effective messenger: a politician, yes, but one whose regular guy affect goes beyond the “Midwestern Dad” jokes. A veteran, an educator, a guy who apparently does not own a single stock, mutual fund, bond, or private equity. There’s an authenticity to Walz that is hard to fake and even harder for his opponents to attack.

He’ll still face plenty, of course: Trump campaign manager Chris LaCivita, mastermind of the “swiftboat” campaign against John Kerry in 2004, has begun attacking his military service, while others on the right have wasted little time going after him on immigration and the unrest in Minneapolis following the murder of George Floyd in 2020.

But Walz has not only helped Harris further energize once-despondent Democrats who are concerned about the dangers of a second Trump term—he is challenging Trump and Vance on the populist terrain Biden had effectively allowed them to take. As Harris put it on Tuesday evening: “Our campaign is not just a fight against Donald Trump—this campaign is a fight for the future.”