Joe Biden has said US Donald Trump has “cloaked America in darkness for much too long” as he accepted the Democratic White House nomination.
The former US vice-president said his rival has unleashed “too much anger, too much fear, too much division”.
Mr Biden’s speech is the culmination of a political career spanning nearly half a century.
He heads into the general election campaign with a clear lead in opinion polls over Mr Trump, 74.
But with 75 days to go until the election the Republican president has plenty of time to narrow the gap.
Speaking from a mostly empty event centre in his hometown of Wilmington, Delaware, Mr Biden, 77, said: “Here and now, I give you my word, if you entrust me with the presidency, I will draw on the best of us, not the worst.
“I’ll be an ally of the light, not the darkness.
“It’s time for us, for we the people, to come together and make no mistake, united we can and will overcome this season of darkness in America.
“We’ll chose hope over fear, facts over fiction, fairness over privilege.”