Rep. Raúl Grijalva (D-Ariz.) will officially back Sanders later this week.
Rep. Alan Grayson says the committee was designed to harm Hillary Clinton.
The Republicans had said they couldn't name any of Clinton's accomplishments.
The Democratic former Ohio governor leads the incumbent Republican senator.
Trump says he has not had to spend any money to date because of TV coverage.
CNN reported that Biden will gather his family this weekend.
The minute-and-a-half-long ad then ends with a plea: “Joe, run."
The former president called the GOP front-runner a "master brander."
Donald Trump and Hillary Clinton continue to lead their parties in those three states.
“You're not taking property. … You're paying a fortune for that property."