President Trump and Joseph R. Biden Jr. appeared onstage together for the first time on Tuesday. It was not exactly a debate.
Shouting, interruptions and often incoherent cross talk filled the air as Mr. Trump purposefully and repeatedly heckled and blurted over his rival and the moderator alike in a 90-minute melee that showcased the president’s sense of urgency to upend a race in which polls show him trailing.