The senator had a series of poor showings in Democratic primaries around the country, ending hopes for a progressive challenger to President Donald Trump.
Bernie Sanders, his top rival for the Democratic nomination, said he would choose a female running mate "in all likelihood."
These are the first campaign events that have been impacted by the outbreak.
He acknowledged that he still needs to do some work in turning out young voters, and he hit the "corporate media" for not treating him fairly.
The former vice president's wife and his adviser took down the protester swiftly at the Super Tuesday rally.
"Like when you chock on your covfefe?" one person fired back online.
The former South Bend, Indiana, mayor struggled to gain momentum in more diverse states.
The gloves came off at the Democratic primary debate in Vegas.
Every candidate faces voter bias, the senator said while addressing a conversation he allegedly had with Elizabeth Warren in 2018.
The Democratic candidates disagreed without getting into any big fights at the final debate before the Iowa caucuses.