KEILAR: One day before the Super Tuesday sequel, former Democratic rival, Senator Cory Booker announcing he's backing Joe Biden. Chris Cillizza joining us now. So, Chris, Booker is just the latest ex-rival to endorse Biden. But there's been several others.</s>CHRIS CILLIZZA, CNN POLITICS REPORTER & CNN EDITOR-AT-LARGE: Yes, that's right, Brianna. It's been an absolute wave since Super Tuesday. This is the Booker endorsement. We know that happened. Let's go to the next screen because this is what's really important. This is where you start to see the disparity in who has endorsed whom. The Biden list is, basically, everyone who ran for president, short of Marianne Williamson, who hasn't endorsed Bernie Sanders. In the undecided list, this is the one I'm focusing on. Sure, you'd be glad to have Kirsten Gillibrand's endorsement, or John Hickenlooper, Castro, et cetera. But Elizabeth Warren's endorsement might actually mean something, particularly if it goes to Sanders. The story line right now is not good for Bernie Sanders. Joe Biden won Super Tuesday in a way no one expected that he would and going to have a delegate lead coming out of it. Michigan, a poll that just came out before I went on air, shows Biden with a big lead there. So he needs to change the momentum and dynamic. This is one thing that might be able to do it -- Brianna?</s>KEILAR: All right, Chris Cillizza, thank you. Moments from now, passengers onboard the virus-stricken cruise ship arriving to be quarantined. Live pictures coming just outside of Oakland, California. Stand by for that.
Booker Endorses Biden & Where Other Ex-Rivals Have Put Support.