Quote Originally Posted by Omanes Alexandrapolites
If your senate popularity drops too low this may result in missions which come with penalties. If it drops even lower a demand for the suicide of your faction leader will be issued. Refuse and civil war breaks out, while acceptance kills your faction leader off giving you a few years of peace before they ask you again. If missions with penalties occur, you may want build up forces on the borders, or even over the borders, with the other Romans - often they remain on the side of the senate during civil wars provoked in this way.
That much I gathered from reading the forums. However, 35 provinces as a hard limit at which point senate popularity starts dropping is a useful advice. I'll get to 35, securing my borders (hopefully by sharing borders only with myself except for a few fronts) then start getting my resources together for the civil war.