Clinton made those remarks during the 2016 presidential campaign, in which she referred to some of her rival Donald Trump's supporters - white nationalists and members of the alt-right - as a "basket of deplorables".
With Sanders winning a small percentage of delegates, and with many states that were scheduled to hold primaries and caucuses in April and May pushing back their contests until June or even later due to health concerns over the coronavirus pandemic, Biden's timetable to clinch the nomination was delayed.
"We are living in a volatile political environment", the then-Democratic presidential candidate said.
A candidate needs at least 1,991 delegates to secure the nomination. "But that's not who we are", the former vice president said. The firm also said numerous polls depicting Biden's growing lead came after the death of George Floyd on May 25.
Biden now has 1,993 delegates, with contests still to come in eight states and three USA territories. The country is crying out for leadership.
Since the COVID-19 crisis shut down the physical campaign trail, Biden has largely been confined to his Wilmington, Delaware home, but this week has reemerged to offer blistering critiques of President Trump's handling of both the virus and the unrest in the wake of the death of George Floyd, an unarmed black man who died after a white Minnesota police officer put his knee on his neck for over 8 minutes.
"Those of us who have served believe the greatness of our military - and the greatness of our nation - depends upon the calls for change in the streets today becoming votes for change in November", the 55 military leaders wrote. "Leadership that can bring us together".
Mr Trump has indicated he is eager to take the fight to Mr Biden who he derides as "Sleepy Joe", and the Democrat has faced a number of difficulties. This is the 77-year-old's third run for the presidency.
Biden had a slow start and recorded his first win in SC at the end of February.
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", Biden said.
At one point, the Democratic primary included dozens of candidates of different races, genders and generations and an openly gay man.
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. Biden has also embraced a plan to forgive millions of Americans' student debt, meaning that he clinches the nomination as easily the most liberal standard bearer the Democratic Party has ever had.