But it was his blowout win in the SC primary in late February, fueled by a late endorsement from influential Congressman and House Majority Whip James Clyburn and overwhelmingly strength with black voters, that rejuvenated Biden's campaign and propelled him to a delegate lead that soon became insurmountable.
"We are living in a volatile political environment", the then-Democratic presidential candidate said.
"The words a president says matter, so when a president stands up and divides people all the time, you're going to get the worst of us to come out", Biden said.
Speaking to an activist who was planning a Friday night march in Biden's hometown, Wilmington, Delaware, the former vice president offered a gentle warning against allowing the protest to lead to destruction.
Biden has been the presumptive Democratic nominee since April, when Vermont Sen.
"This is a hard time in America's history", Biden's statement said.
Biden, who launched his campaign in April of 2019 and was labeled an early frontrunner for the Democratic nomination, stumbled through the first three nominating contests, finishing a distant fourth in the Iowa caucuses and fifth in the New Hampshire primary. The country is crying out for leadership. And civil unrest has erupted in dozens of cities following the death of George Floyd, a black man who died when a white Minneapolis police officer pressed his knee onto his neck for several minutes even after he plead for air and stopped moving. "We have to appeal to that and we have to unite people - bring them together".
It's a confluence of events that no US leader has faced in modern times, made all the more complicated by a president who has at times antagonized the protesters and is eager to take the fight to Biden.
Biden's strong showing in states such as North Carolina, Virginia, Tennessee and Texas reinforced his status as the preferred Democratic candidate of African American voters - but the relationship has not been without its strained moments.
"Hate didn't begin with Donald Trump, it's not going to end with him", he said.
Mr Trump and Mr Biden have already clashed on these issues, which look set to dominate the polls in November.
At one point, the field had more than 20 candidates, with contenders dropping out as their chances faded.
Trump, for his part, has made harsh, denigrating and insulting remarks about many individuals as well as whole groups of people and countries, including African Americans, Mexican immigrants, Muslims, women, Jewish donors, and Haiti and some nations in Africa.
It's not unusual for a Democratic nominee to clinch the party's nomination in early June.
The New York Times on Wednesday reported Trump is trailing Biden even in private campaign polls.