PHILADELPHIA, PA - MAY 18: Former U.S. Vice President and Democratic presidential candidate Joe Biden speaks during a campaign kickoff rally, May 18, 2019 in Philadelphia, Pennsylvania. Since Biden announced his candidacy in late April, he has taken the top spot in all polls of the sprawling Democratic primary field. Biden's rally on Saturday was his first large-scale campaign rally after doing smaller events in Iowa and New Hampshire in the past few weeks. (Photo by Drew Angerer/Getty Images)