Bernie Sanders speaks to supporters at a campaign rally in Ventura, California, Thursday, May 26, 2016. Sanders is barnstorming California ahead of the state's June 7 primary. He's in a tight battle with Hillary Clinton in the state, but he needs a landslide win to make a dent in her huge delegate lead for the Democratic presidential primary.
One wild card introduced into the race Thursday is the possibility of a Sanders debate against presumptive GOP nominee Donald Trump.