Political sermons are probably more common in poorer countries, I imagine. I'm from a poorer country and the Catholic masses I used to attend would have priests talk about social justice. I don't recall the priests singling out any particular politicians or groups but we all know who they are talking about. Maybe in the past, priests were more direct in criticism. The liberation theology movement in the latter half of the 20th century was instrumental in toppling many dictatorships. I think there were couple of Catholic priests who were assassinated for voicing out against dictators in Latin America.