“Biden catapulted to prominence in the 1970s by rebelling against school integration through busing. Biden reached across the aisle to his friend Jesse Helms — one of the most virulent racists in modern politics — to launch relentless verbal and legislative attacks on school busing that, if taken literally, would have scaled back the government’s power to desegregate more broadly, and he bragged that he’d made it okay for other liberals to do so.”