Bernie Sanders has a long way to go yet before he locks up the Democratic nomination. He fell short of expectations in both Iowa and New Hampshire, winning both by the thinnest of margins. (And Pete Buttigieg may yet emerge with more delegates from those first two contests.) His victory in Nevada was a knockout, but the South Carolina and Super Tuesday contests could still revive Joe Biden’s fortunes or show that Elizabeth Warren didn’t really abort Bloomberg’s campaign by humiliating him in last week’s debate.