CNN host presses Bernie Sanders on why Kamala Harris is campaigning with Liz Cheney and not him

CNN host Jake Tapper pressed Sen. Bernie Sanders on Sunday on why Vice President Kamala Harris is out campaigning with Liz Cheney, a Republican, rather than the progressive Vermont senator.

"What does it say the Kamala Harris is starting this week with only 16 days left, campaigning with Liz Cheney, a very conservative former congresswoman, daughter of Dick Cheney, obviously, but she has not yet held a public campaign event with you, arguably the leader of the progressive movement in the United States?" Tapper asked. 

Cheney...