There are also the nuts and bolts political considerations that Sanders doesn’t focus as much on, but his team pays close attention to: He’s the one with the massive email list. Alone in the Democratic field, he’s the one who had 40,000 people watching various livestreams of his State of the Union response. He’s the one whose team thinks he could on day one raise more money online and get more attention than any of the other candidates.
Sanders believes he continues to have the strength in Iowa and New Hampshire to either win or come close there—especially, with other candidates fragmenting support and lowering the bar for what it will take to win. Likewise, in a South Carolina primary that has both Cory Booker and Kamala Harris competing for African-American votes and likely Joe Biden drawing on his own decades of connections there, Sanders sees a path to slip through and win.
Biden in the race, after all, would make it so that the senator isn’t the only white man in his 70s in the field.