Claims to fame: President Barack Obama's sidekick from 2009 to 2017 and a U.S. senator from Delaware from 1973 to 2009 has White House experience and appeal among working-class voters that President Donald Trump won over in 2016.
Biggest weaknesses: He is among three candidates who would be the oldest individual ever elected as president, has a history of gaffes and has been accused by some women of uninvited touching that was nonsexual.
Miami moment: He didn't forcefully rebut attacks by Sen. Kamala Harris on race and his school busing position during the 1970s. "My time is up," he said at one point.
Candidate visits to Michigan: Candidate visits to Michigan: July 24 for the NAACP national convention in Detroit