The strategic concept (or political guide) of uniting the left and center is one that I’ve found helpful over the years. But in present circumstances, it can be more trouble than its worth if it takes out of field of vision the progressive-liberal-democratic bloc that inhabits space between the two or collapses this bloc into the center. Think about the massive coalition that defeated Trump and elected Biden. A broad swath of it doesn’t fit comfortably into either category – left or center. What is more, if there is a dominant bloc in the Democratic Party, it is this bloc.