CUPW Retreats Under Mounting Pressure. The likely reason CUPW stepped back from the full strike is that it’s becoming clear to many observers that the union is now contributing to the long-term decline of the very workers it claims to protect. It’s reasonable to assume CUPW’s move is calculated—a means to preserve its position and live to fight another day. However, the reality is stark: the primary issue looming over Canada Post is its defined benefit pension plan. With more postal workers retiring and fewer incoming contributors, the pension burden is becoming more difficult to manage, especially as Canada Post remains in the red.