'The country is crying out for leadership' -Biden

Speaking in Philadelphia – a city rocked by sometimes violent demonstrations in recent days – the former vice president sought to draw a vivid contrast between himself and Trump, whom he will likely face in the Nov. 3 general election.

He said the killing of George Floyd, the African-American man who died at the hands of Minneapolis police last week, was a "wake-up call" for the nation that must force it to address the stain of systemic racism.

"We can’t leave this moment thinking we can once again turn away and do nothing," Biden said. "We can’t."