CHARLESTON, SOUTH CAROLINA - FEBRUARY 25: Democratic presidential candidate former Vice President Joe Biden speaks as Sen. Bernie Sanders (I-VT) (C) and Sen. Elizabeth Warren (D-MA) (L) look on during the Democratic presidential primary debate at the Charleston Gaillard Center on February 25, 2020 in Charleston, South Carolina. Seven candidates qualified for the debate, hosted by CBS News and Congressional Black Caucus Institute, ahead of South Carolina’s primary in four days.  (Photo by Win McNamee/Getty Images)