Joe Biden called on Americans to demand change when it comes to police brutality against African Americans, saying he'd spoken with George Floyd's family and that "none of us can stay silent. None of us can hear the words 'I can't breathe' and do nothing." Why it matters: The livestream remarks by the presumptive Democratic presidential nominee had the look and sound of an address to the nation — and came right before President Trump was set to give remarks.Trump tweeted overnight that protesters in Minneapolis were "thugs" who were "dishonoring" Floyd's memory, and he warned that "when the looting starts, the shooting starts."What they're saying: Biden said Floyd's relatives are "a close, decent, honorable family loving one another."One of the things everyone must be able to do: Breathe.""The original sin of this country still remains today, and sometimes we manage to overlook it. We just push forward with a thousand other tasks in our daily life, but it's always there." Biden spoke about other black Americans who've died at the hands of police recently, including Ahmaud Arbery in Georgia and Breonna Taylor in Kentucky."It's a list that dates back more than 400 years," Biden said, one that affects black men, black women and black children.The big picture: Biden implored white Americans to consider systemic injustices against African Americans more broadly."Imagine if every time your husband or daughter, son or wife left the house and you feared for their safety from bad actors and bad police," Biden said. "Imagine if you have to have that talk about not asserting their rights, taking the abuse given to them, just so they could make it home."He called Floyd's murder "an act of brutality so elemental it denied him of his very humanity, it denied him of his life."Earlier in the week, Biden addressed Floyd's killing before a virtual roundtable with Pennsylvania Gov. Tom Wolf, comparing it to the 2014 killing of Eric Garner who was heard on tape repeatedly saying, 'I can't breathe' while a New York police officer used an illegal chokehold on him.