De Blasio is sworn in by Sanders (photo: Benjamin Kanter/Mayor's Office)

Mayor Bill de Blasio, a Democrat, was sworn in for a second and final term at City Hall on a frigid Monday afternoon, in a ceremony attended by nearly a thousand people and starring United States Senator Bernie Sanders of Vermont.

De Blasio’s oath of office was administered by Sanders, the popular progressive leader who has championed policies to benefit middle- and working-class Americans, similar to the mayor’s own