Clyburn's endorsement of former Vice President Joe Biden on February 26, 2020, three days before the South Carolina primary, was considered pivotal in the 2020 Democratic Presidential nomination contest. Several analyses have determined the endorsement changed the trajectory of the race, due to Clyburn's influence over the state's African-Americans, who make up the majority of its Democratic electorate. Prior to Clyburn's endorsement, Biden had not won a single primary and had placed fourth, fifth, and a distant second in the Iowa, New Hampshire, and Nevada caucuses and primaries respectively. Biden utilized momentum from his win in South Carolina to take a delegate lead on Super Tuesday and clinch the nomination a month later, and eventually win the presidency in November. At Biden's Inauguration, former President George W. Bush confided in Clyburn that he believed without his endorsement Biden would not have been elected.