Heading into the debates, what do progressive voters want to hear from the candidates?

Tonight, 10 Democratic presidential candidates will appear on stage for the first of several debates stretching from now until well into next year. With more than 20 candidates officially vying for the party’s nomination — welcome Joe Sestak, who entered the fray just this week — the “first” debate is actually split across two nights this week, with another 10 candidates fielding questions on Thursday.

For many voters, this week’s debates will be their first encounter with the most ...