Philadelphia They call him Teflon Don for a reason: attacks on Donald Trump never stick. What explains this strange resilience? It might have something to do with who’s attacking him. Let’s look at the pantheon of main adversaries in the Trump cosmos, Lyin’ Ted, Little Marco, Crooked Hillary, and Pocahontas, aka Goofy Elizabeth Warren. We have two relatively young Latinos (Ted Cruz and Marco Rubio) and two women (Hillary Clinton and Elizabeth Warren). It’s easy for Trump to shred their credibility with a sneer and a slur. To his largely white, mostly older fans these people buck the tradition of what a leader should be. But Joe Biden doesn’t buck that archetype at all. And he just went for Trump’s dress shirt-encased jugular. “This guy doesn’t have clue about the middle class,” said Biden. “He doesn’t have a clue, period.” The Wells Fargo arena erupted into chants of “Not! A! Clue!” Biden was perfect for this job. He’s an older white guy who hails from a working-class family in Scranton, PA, who’s famed for his occasionally profanity-laced straight talk. Pretty much exactly what Trump prides himself on, in other words, plus bona fide middle-class roots. Trump can’t play to unspoken biases against non whites or women to foil character attacks from a man whose outward trappings of trustworthiness are the same—or even superior—to his own. The brilliance of Biden’s line of attack is due to more than just his status, though. Common criticisms of Trump focus on his being dangerous for America due to his unwise policies. As evidenced again today—when he encouraged Russian hackers to attack the US—his supporters don’t really care. His brash indifference to preserving world order seem like strength. And Crooked Hillary is always fair game. It’s harder for Trump to defend his character, however, without looking weak. This passage of Biden’s speech has got to be one of the sharpest yet—and it cuts right into one of the things Trump is proudest of, his reality TV show, The Apprentice. “His cynicism is unbounded. His lack of empathy and compassion can be summed up in a phrase for having made him famous: You’re fired!” said Biden, referring to the trademark refrain of The Apprentice. “Think about that. How can you take pleasure in the saying, ‘You’re fired?’” He continued, “Think about everything you learned as a child. No matter where you were raised, how can there be pleasure in saying you’re fired? He is trying to tell us he cares about the middle class. Give me a break. That is a bunch of malarkey.” His rally crowds find Trump’s meanness entertaining when it’s directed at the cartoon villains like Lyin’ Ted or Crooked Hillary. Biden did a good job reminding the viewing audience that Trump’s on-camera sadism was directed at regular people for 14 seasons of The Apprentice. Finally, to counter the baleful vision of America Trump encapsulated in his convention speech last week, Biden went with patriotism. ”We do not scare easily. We never bend easily, we overcome and we always, always, always move forward,” he said. ”We are America, second to none—and we own the finish line.”